Compressor Messer: Remove -Xss argument.

The commit description says it best:

```
It looks like in #4, someone was under the impression you can pass
arbitrary JVM flags here. This is, in fact, not the case. As a result of
this chage we were getting usage information on the console every time
we tried to invoke yui.
```

I can't figure out why the author originally committed code doing this, but JVM stack size adjustments would definitely need to be made at the invocation of the JVM itself, not at the invocation of YUI.