Update build_command method

Updated build command method to capture interrupt and kill all processes. Solves a weird problem where cucumber continues to run.

Refactoring and .travis pre builds

1. Added build command unit tests to get back to 100% code coverage
2. Updated executable and removed interrupt
3. Updated cukesparse handing of running cucumber command
4. Updated travis.yml to create pre-release gems

Small fixes

• Fixed coveralls coverage issue as was incorrectly 100% due to where cukesparse was required.
• Added .DS_Store to .gitignore