Move test directory to top level

The test directory should be in the top level, separate from the rest of the
application. A future commit will create a separate pip.req file for test
dependencies only.
Update test README and structure

The testing directory is now separate from the main application and the
instructions for testing have been updated. It will obviously assume that shrunk
has been installed in a virtualenv but for now it won't be listed in pip.req.

Perhaps a future commit will add a setup.py; this will allow for easy testing
with:

    (virtualenv) $ python setup.py sdist
    (virtualenv) $ pip install --no-index=--find-links shrunk0.1/ shrunk

or something similar.
Update .gitignore to ignore compiled files

Now also ignores __pycache__ directories generated by iPython.
Begin db module version 0.1

Initialized an empty Python database module.
Add shrunk_client.py skeleton

db.ShrunkClient provides a convenient interface to the database-level operations
for the shrunk app. The main application logic should use this class to interact
with the database rather than accessing it directly.
Update shrunk_client.py

This completes a first draft of the basic API functions for db.ShrunkClient. It
will need testing.

An important missing feature is the short URL generation; the random strings of
letters and numbers are merely for testing purposes at this point.
Add database unit tests

This has a few simple unit tests for the database layer. It is meant to be run
with nose.
Fix name typo in comment strings

Using the new, correct 'shrunk' name.