Update .travis.yml
Fix build script dependencies
Auto-import translations
Downgrade target/compile sdk version to 19
Fix .travis.yml build command
Add test-key.keystore for testing builds
Make Travis-CI use test-key to build
Downgrade Android support library to version 19+
Downgrade Build tools to version 19.1
Downgrade Build tools to version 19.0.3
Revert "Downgrade Build tools to version 19.0.3"

This reverts commit 7ca8aa0dde7f7ae279481ea6e41e97eee18a8213.
Add Travis-CI build status icon

Which is failing at this moment, because of lack of build tools version 19.1.
Add 'How to build using public test key' to README.md