Remove Closure Minifier from Core (SquishIt.Framework)

[AlexCuse]

The closure minifier creates a security vulnerability (see https://groups.google.com/forum/#!topic/squishit/dhH3i0vOAsU). I don't think this is actually used very much because there are a few good in-process options available, so removing it from the core library makes sense.

Could make available as a separate package if need be.

Post any questions or concerns in here.