Revert "Use CodeJail with FSIZE support, and default to 50k"

This reverts commit 89c48f4a3047ca6cf0985b92e004fb584dd22a30.

Conflicts:
	requirements/edx/github.txt
Merge pull request #468 from edx/cale/revert-code-jail-changes

Revert "Use CodeJail with FSIZE support, and default to 50k"