use gulp; add .travis.yml

 - use Gulp instead of Grunt
 - add .travis.yml file

Signed-off-by: Andre Meyering <info@andremeyering.de>
Merge branch 'master' of https://github.com/archer96/ng-i18next

* 'master' of https://github.com/archer96/ng-i18next:
  use gulp; add .travis.yml

Conflicts:
	CHANGELOG.md