TST: Add nose-ignore-docstring plugin to requirements and setup.cfg

So that docstrings can be added for test documentation, but suppress
those docstrings in test output by default.

etc/requirements_dev.txt

@@ -1,6 +1,7 @@
 # Testing
 nose==1.3.0
 nose-parameterized==0.2
+nose-ignore-docstring==0.1
 
 # Linting
 

setup.cfg

@@ -1,7 +1,4 @@
 [nosetests]
 verbosity=2
 detailed-errors=1
-
-# Drop into debugger on failure
-#pdb=0
-#pdb-failures=0
+with-ignore-docstrings=1