For Review. Starter feature. Locale descriptions in switching language modal.

I came here from the starter feature list and https://github.com/adobe/brackets/issues/1461 .
This is my first pull request ever, and its for review. 

There is default behaviour to show just the locales (as it is now). It will lookup a i18n for a locale in the strings.js file of the language. I also added german translations for all current locales.

I think that the translation of every locale should be in that strings.js file as a part of the i18n (does not matter how it is displayed), even if the modal UI is refactored in some time.

I did not write on the mailing list before, because it is just a small hack.