Remove the GC disable/enable in the before/after blocks.

It's not clear why were were doing this but the code was implemented in commit:
ff4b5f010ab115a3eec40703b40096ecbe44db34

And refined in commit: 3e637725c2c2ce1fea69c5a1491046370f8d7408, with a message including:
"...Hopefully this doesn't reintroduce the GC segfault."

I believe this was added back when we were using ruby 1.8.7 and possibly libxml-ruby/rexml with soap4r.  Since we're way beyond 1.8.7 with 1.9.3 and soon 2.0, we should remove this and fix it if it re-occurs.