License change to Apache License Version 2.0 (madmaze#245)

* Update LICENSE file

Changing the license of this repository according to the vote from madmaze#237 (Petition to change license to Apache 2.0 (to match tesseract-ocr))

* Update license definitions and bump version 0.3.1

* Update README to reflect license change

Ref: madmaze#237 
[skip ci]

Author: int3l