add new result file to today's archive (.tar.bz2), create if archive nonexistent
change backend to support archived results, remove archive after finished sending
archive files once every x files (x files per archive)
in backend, load archive compression type from config
removed encoding config value
Merge pull request #73 from rpanah/results_archiving

Results archiving
Merge remote-tracking branch 'origin/master' into kill_upload_on_failure

merging master into feature branch

Conflicts:
	centinel/backend.py