Use batch_pos_tag to calculate POS tags

Calculating POS tags for an entire document without splitting to
sentences first may be wrong.

Also, we now [also] use doctests, so nosetests is configured to run
those. nosetests will read setup.cfg for the project.
Simplify memoize, enable pickle-compatibility

This may prove useful for caching results of Analysis.
memoize: Add doctest

Also properly @wrap...
gitignore: Ignore convenience test data
Implement caching
Increase timer frequency
Add split pos tags by sentence

Helps with #20
contractions: Properly count contracted forms

Wouldn't should is tokenized as ("would", "n't"), not ("wouldn", "'t").
test_analyez: Properly test multiple attributes
Attributes no longer have to be specified

attributes, variant_attributes are now optional. Actual attributes in
analyze.py output will be collected from actual results.
Clean up nosetests output

Logging output is explicitly captured by nosetests.
Adding cohesive markers - not finished!