Switching from a static copy of LESS as a submodule pointed at 1.6.3 release.

This pull request does only two things, it removes the static copy of less and adds a LESS as a git submodule.  If you guys would be willing to pull this in that would be awesome!

I mentioned this in the forums the other day (http://forums.enyojs.com/discussion/1977) but I am working on a project where I am creating some basic enyo kinds which map to the basic components of twitter bootstrap.  As of bootstrap version 3.1 the version of LESS which is included with enyo can no longer compile the less used for bootstrap.

Looking into this I found that enyo appears to have a static copy of LESS that dates back a couple of years.  It seems more natural to have less be a git submodule.  That way we can easily upgrade again next time and enyo already uses git submodules in its bootplate.  The great news about this change is that it shouldn't break anything.  The dist directory still contains less 1.3.3 which is referenced by debug.html in the bootplate but I also tested compiling the LESS from both enyo and onyx and version 1.6.2 seemed to compile everything just fine.