Simplify the name of a lock

The longer the name the hardest to deal with it by means of a
human's eye.
Support setting the timeout for a lock
Fix code in order to be compatible with python3
Improve the readability of an expression

Thanks for spotting that one, @marcelometal.
Support Python 3.4
Add travis-ci build file and status to readme
Draft a new release, 0.5.1