Backport of c5d9e7e PR719 to 0.9.x
Adding tests for the graphite.render.hashing.hashRequest function.

Conflicts:

	webapp/tests/test_render.py
Removing stripControlChars function, as it's no longer needed.
prune trailing whitespace
Merge pull request #764 from esc/0.9.x-caching-request-hashfix

0.9.x caching request hashfix