Using YUI compressor to compress all files in one shot rather than spawing a JVM per file.

By compressing all files in a given directory in one shot, we can save the time it takes for the task to perform a JVM lifecycle operation per file YUI tries to compress.
PENDING: I've not moved the css_sass directory compression to this new style yet.

```
Stats:
Completed in 3m15.259s (branch: master)
Completed in 2m16.083s (branch: faster-compression)
```