resourceloader: Remove MW cacheEpoch from module version hash
This seems quite nuclear. I'd actually like to deprecate the
wgCacheEpoch variable more generally in favour of a handful
of more specific version constants, but as starting point,
remove it from the hash used for load.php urls and localStorage
The latter is also controlled by wgResourceLoaderStorageVersion
Also ref T32956 about a more standalone ResourceLoader.