Now each yui module is only read and compiled once, instead of twice; once by the resource store and once by the yui loader. Modules are read and compiled in the resource store and the YUI add method is hooked to obtain yui meta information, at the same time non-client side yui modules are added using the YUI.add method.
Removed clearing of langLoaderCreated, since this is now done in yui.preloadResourceVersions.
Updated history.
Not returning invalid yui modules through parseResourceVersions; making sure not to call YUI.add twice on a module, since mojito will use the first one and so the module should not be replaced.
Mocking store.YUI object.
Creating runtime YUI object in preloadResourceVersions such that store.preload can be called multiple times without errors. YUI object is created in a sandbox.
Merge pull request #1375 from yahoo/read-yui-files-once

Read YUI modules only once
Merged develop.