Javascript Region Folding

See [Discussion] (https://groups.google.com/forum/#!topic/ace-discuss/JkeDqTJAUso)

*Harutyun Amirjanyan: but since vs and webstorm support i am not opposed to including it (either default or as an extension) if required changes are small
create the pull request and i'll have a look.*
End range should be at end of line as we don't want to display the
'#endregion' text after the fold widget (this is consistent with cstyle
region comment folding).