Fix #112 - Add continuous integration via Travis CI.

Increment build tools to 19.0.1, apparently 19.0.0 aren't available via Travis CI (fetching fails with HTTP 404 error).

Matching buildToolsVersion in build.gradle with build tools version in .travis.yml file.
Update to #112 - Add Travis status badge to README.
Merge pull request #115 from CUTR-at-USF/Travis3

Fix #112 - Add continuous integration via Travis CI.