Reintroduce sources command line option for retrieving gecko and platform revisions
Merge pull request #3 from davehunt/sources

Bug 840793 - Reintroduce sources command line option for retrieving gecko and platform revisions
Bug 847953 - Don't reset the testsuite for every new metric we add
Bumped version number to 0.2.1
Fall back to the sources.xml file when retrieving the Gaia revision from the application.zip fails
Use the sources command line option in mozperf.py