Merge pull request #159 from manandbytes/travis-ci

Use latest Android SDK for Travis CI builds
Let Travis run 'mvn install' for us

By default [1], Travis will run 'mvn install -DskipTests=true' for
Maven-based projects. This will build and install all required
dependencies (including our own artifacts).

[1] http://about.travis-ci.org/docs/user/languages/java/#Dependency-Management
Run integration tests only

As all dependencies has been downloaded, run in offline mode to
eliminate network-related delays.