Add .travis.yml

- Add .travis.yml for Travis CI.
- Minor syntax in tests to prevent error when running on Travis CI Xcode 6.0.
- Make Quick-iOS scheme shared to enable building from the command line.
- Separate "test" rake task into "test:ios" and "test:osx".

Fixes #25.
Merge pull request #166 from modocache/travis

Add .travis.yml