ci: Travis improvements (#1980)
ci: Travis improvements (#1980)

@TryHardDood Thank you once again! Great contribution

* Run tests, build library and documentation automatically when pushed to master.
* Deploy documentation to gh-pages branch when pushed to master.
* Run just the tests when a pull requests is created.

* Run tests, build library and documentation automatically when pushed to master.
* Deploy documentation to gh-pages branch when pushed to master.
* Run just the tests when a pull requests is created.

**Other changes:**
* Switched to node 11. (Because gulp fails when the library is built with node 12)
* Added quick workaround until #1959 is fixed.

closes #1965 
trimox/angular-mdc-web,trimox/angular-mdc-web