Added a global spock extension to barf out the repose_log !

On every failure, the repose log will be barfed to standard out.

Perhaps now I can figure out what actually fails
Clean the log file before every spec run, no matter what.

Turns out we're not really cleaning the log file every run.

Our runs aren't very sanitary :(
Merge pull request #1128 from rackerlabs/improved_functional_testing

Improved functional testing