Add contributors license agreements and instructions on how to contribute.

CONTRIBUTING.rst

@@ -0,0 +1,94 @@
+# How to contribute
+
+Third-party patches are welcomed for improving Segpy. We simply can't
+access the huge variety of SEG Y files produced by a myriad of other
+systems.
+
+Although we want to keep it as easy as possible to contribute changes that
+get things working in your environment, there are a few guidelines that we
+need contributors to follow so that we can have a chance of keeping on
+top of things.
+
+## Getting Started
+
+The easiest way to help is by submitting issues reporting defects or
+requesting additional features.
+
+* Make sure you have a [GitHub account](https://github.com/signup/free)
+* Submit an issue, assuming one does not already exist.
+  * Clearly describe the issue including steps to reproduce when it is a bug.
+  * Make sure you mention the earliest version that you know has the issue.
+* Fork the repository on GitHub
+
+## Making Changes
+
+* You must own the copyright to the patch you're submitting, and be in a
+  position to transfer the copyright to Sixty North by agreeing to the either
+  the [Individual Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-individual-cla.pdf)
+  (for private individuals) or the [Entity Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-entity-cla.pdf)
+  (for corporations or other organisations).
+* Make small commits in logical units.
+* Ensure your code is in the spirit of [PEP 8](https://www.python.org/dev/peps/pep-0008/),
+  although we accept that much of what is in PEP 8 are guidelines
+  rather than rules, so we value readability over strict compliance.
+* Check for unnecessary whitespace with `git diff --check` before committing.
+* Make sure your commit messages are in the proper format.
+
+````
+    Issue #1234 - Make the example in CONTRIBUTING imperative and concrete
+
+    Without this patch applied the example commit message in the CONTRIBUTING
+    document is not a concrete example.  This is a problem because the
+    contributor is left to imagine what the commit message should look like
+    based on a description rather than an example.  This patch fixes the
+    problem by making the example concrete and imperative.
+
+    The first line is a real life imperative statement with an issue number
+    from our issue tracker.  The body describes the behavior without the patch,
+    why this is a problem, and how the patch fixes the problem when applied.
+````
+
+* Make sure you have added the necessary tests for your changes.
+* Run _all_ the tests to assure nothing else was accidentally broken.
+
+## Making Trivial Changes
+
+### Documentation
+
+For changes of a trivial nature to comments and documentation, it is not
+always necessary to create a new issue. In this case, it is appropriate
+to start the first line of a commit with 'Doc -' instead of an issue
+number.
+
+````
+    Doc - Add documentation commit example to CONTRIBUTING
+
+    There is no example for contributing a documentation commit
+    to the Segpy repository. This is a problem because the contributor
+    is left to assume how a commit of this nature may appear.
+
+    The first line is a real life imperative statement with 'Doc -' in
+    place of what would have been the ticket number in a
+    non-documentation related commit. The body describes the nature of
+    the new documentation or comments added.
+````
+
+## Submitting Changes
+
+* Agree to the [Individual Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-individual-cla.pdf)
+  or the [Entity Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-entity-cla.pdf)
+  by attaching a copy of the current CLA to an email (so we know which
+  version you're agreeing to). The body of the message should contain
+  the text "I, <your name>, [representing <your company>] have read the
+  attached CLA and agree to its terms."  Send the email to rob@sixty-north.com
+* Push your changes to a topic branch in your fork of the repository.
+* Submit a pull request to the repository in the sixty-north organization.
+
+
+# Additional Resources
+
+* [Individual Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-individual-cla.pdf)
+* [Entity Contributor License Agreement](https://github.com/sixty-north/segpy/blob/master/docs/legal/segpy-entity-cla.pdf)
+* [PEP 8](https://www.python.org/dev/peps/pep-0008/)
+* [General GitHub documentation](http://help.github.com/)
+* [GitHub pull request documentation](http://help.github.com/send-pull-requests/)