BLD: Package all zipline.* modules when building eggs.

Rather than specifying only the package "zipline" in setup.py, use
`find_packages` to find all the subpackages as well, so they (or, most
specifically, their `__init__.py` files) are properly packaged in the
egg file.

setup.py

@@ -191,7 +191,7 @@ setup(
     description='A backtester for financial algorithms.',
     author='Quantopian Inc.',
     author_email='opensource@quantopian.com',
-    packages=['zipline'],
+    packages=find_packages('.', include=['zipline', 'zipline.*']),
     ext_modules=ext_modules,
     scripts=['scripts/run_algo.py'],
     include_package_data=True,