fixed __init__ to properly extract_words from SentimentDoc

SentimentDoc and sentiment checking should properly work now and be properly OOP'd
updated doctests, docstrings in data.py
made HowManyDoc a base class, SentimentDoc inherits it

so that we can return just that one analysis object to the webpage for rendering
added frontend sentiment output, removed circular import by moving classes into data.py
fixed maxphrase length checking