Removed JS2 work (has been moved to the js2-work branch). Has been lightly tested...

Removed JS2 work (has been moved to the js2-work branch). Has been lightly tested, should mostly work. Some of the more complicated associated changes are listed below.

* Reverted HttpFunctions.php to r45549 and renamed wgSyncHTTPTimeout back to wgHTTPTimeout
* Edited out the asynchronous features from UploadFromUrl. Made fetchFile() use the curlCopy() function from new-upload r47811 instead of Http::doDownload(). Wrote my own URL validity check to avoid having to use either of the two buggy precedents.
* Removed UploadFromChunk
* Removed chunk upload and background status from ApiUpload.php
* Reverted r54669, use of addScriptClass()
* Left getHeadScripts() in its current location (OutputPage) instead of moving it back to SkinTemplate, just added wikibits.js to it to replace the removed addCoreScripts2Top()