classes for label, sentence, and evaluation

FIXME: need to implement for label, sentence, and evaluation
Merge branch 'master' into sanghee
sample labels.txt file for evaluating rate
refactoring classes into each files
refactor method names following ruby coding convention

'Methods should be verbs.' for following ruby coding convention.
http://rails.nuvvo.com/lesson/5017-ruby-coding-convention
from labels.txt, making a set of labels (only a file not directory)

FIXME: need to implement read_dictionary.
At this time, I want to read only a file to make a set of labels
for rapid prototyping.
Evaluating match rate between labels from captured image and res string
Refactor some methods under ApkContentsEvaluator

Storing evaluation per case and per apk as attributes will allow
this class to export them to various formats such as csv.
Test ApkContentsEvaluator with sample data

Using following command:
$ ruby ace_driver.rb demo/data/labels/labels.txt demo