began to add named entity support

uses the stanford NER package to identify named
entities in a sentence. Assumes it's running on localhost
at port 8080.
getting entity-based sentiment working

altering the representation of the sentence in order to
make it easier to compute the orientation score - instead
of
"I hate Northeastern University" ->
["I", "hate", "Northeastern", "University"]
it should be
["I", "hate", "Northeastern University"]

for every entity that appears in a sentence.
holy shit it worked

it took a while but parse_entities is working now
(functional programming woo!)
Sentence class is looking more developed.

should be able to streamline the classifier code now
sentiment towards a particular entity

Also lots of documentation and type annotations for most functions.

can now do score_all_entities(sen, entity) to get dict of entity ->
score, where score ranges from [-1, 1]
Merge pull request #2 from dcalacci/entity-based

adding entity-based sentiment analysis