Use jquery.i18n for standalone i18n

VisualEditor.php:
* Make jquery.i18n a dependency of ext.visualEditor.standalone

makeStaticLoader.php:
* Remove ve.init.platform.addMessages() call with PHP-generated messages
* Add fake module for jquery.i18n
** Needed because the module might come from MW core
** Also add special treatment for fallbacks.js and language scripts

ve.init.sa.Platform.js:
* Remove basic message system, replace with jquery.i18n
* Add initialize method that loads messages for current language and
  fallbacks

ve.init.sa.Target.js:
* Wait for the platform to initialize before actually doing things
* Add .setup() method to allow callers to short-circuit this process
** This is convenient for callers of ve.init.sa.Target in the test suite

ve.ce.test.js:
* Use existing ve.test.utils function for creating a surface

ve.test.utils.js:
* Call .setup() on the target so we can get a surface synchronously

ve.init.Platform.test.js:
* Make these tests async, wait for the platform to initialize
* Allow for missing messages to be output either as <foo> (MW)
  or foo (jquery.i18n)
* Get rid of message clearing code, namespace test messages instead

Change-Id: Iac7dfd327eadf9b503a61510574d35d748faac92
Merge "Use jquery.i18n for standalone i18n"