Ignore the docs build directory
Add docstrings to pypump.Client, remove class-level attributes

The class-level attributes weren't really used as class level
attributes, were more of a shorthand "here's what attributes we have".
Since we're adding proper docstrings, that's no longer needed.
Documenting the PyPump class
Removing unused class args
Note about distinction between the key types
Add store object to store data
Add testing store
A few English errors

I guess the store docs are still WIP, so I'll leave them for the most part
NotImplemented ==> NotImplementedError

>>> raise NotImplemented()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'NotImplementedType' object is not callable
Add unit test for store class
Fix problem with JSONStore not saving to disk
Remove Kr theme and add fix tutorial for store