V4.0.Update2.Preview-12.18.2015

Contains all commits to vs2015 for this repo up to : https://github.com/Microsoft/visualfsharp/tree/vs2015
Updated version numbers to vsix manifests, to enable autoupdate via gallery.

Includes this fix: fix problem with loop optimization (#742)

Requires VS 2015 RTM : https://www.visualstudio.com/en-us/downloads/visual-studio-2015-downloads-vs.aspx
This preview binaries are released for use under a proprietary license.

Source code is Licensed Apache 2.0

For additional language packs install fsharp_bundlelp.exe after installing fsharpbundle.exe