Dependency updates and improvements

- Updated bcrypt dependency to a more maintained fork from [opscode/erlang-bcrypt](https://github.com/opscode/erlang-bcrypt), which fixes some issues for us while trying to integrate erlpass/bcrypt.
- Introduced Travis CI support - you just have to signup on [Travis](https://travis-ci.org) with your GitHub account and turn on the Travis service hook for erlpass
 - Implemented a Makefile for more convenience
 - Updated rebar to a more recent version compiled with R13B03 to support Travis builds >= R14B02
- Fixed Proper dependency version to 1.1