s/lang/locale

 * Deprecated moment.lang(), moment.langData(), moment#lang, and
 duration#lang

 * Added moment.locale(), moment.localeData(), moment#localeData, and
 druation#localeData

 * Added moment.defineLocale() that defines a locale but doesn't set it
 as the global locale (#1750)

 * Removed the hack in the language concatenator that set the language
 to English.

 * Refactored internal code to use moment#localeData instead of local
 functions, and set the language directly on the moment instance at
 creation.

 * Moved all the files and changed the build scripts so that everything
 lives is named "locale" instead of "lang", e.g. the locale files under
 the "locale" directory.

 * I did *not* include build-generated changes like component.json and
 the concated locale files, but I did inspect them to see that they look
 right.
incorporating ichernev comments
defineLocale() now returns the actual locale. Removed tests for the return statement in the locale definitions.
Fix deprecation warning on moment().locale()
some reverse compatibility
fixing tests
fix jsc error
Merge pull request #1761 from icambron/language_rework

s/lang/locale