Added Locale Service. Minor Controller Refactoring.

Hi there!

I started extracting some "buisiness" logic into a seperate provider/service. My goal, also in preparation for angular 2.0 some day, is to have as much of non binding logic to fit in services. So the migration won't be to much of a pain one day.

I started with this small chunk because it was just easy to extract. So that the monster SyncthingController can shrink in size over time.

Regards,
Dennis
Although it is kind of a bad taste, to have $rootScope dependencies in a service, we could do so here. I definetly see your point. The way I would preferr, is to keep the event handler in a controller/directive and pass the event to a service handler. Catch in controller/directive, handle in services. 

IMHO services should be as isolated as possible to the "UI" and related APIs. Since $rootScope and $scope is directly related to UI and will extinct in angular 2.0, I would have a bad feeling here.