Fix a bug where results_email was being ignored

Referring to the setting in ~/.teuthology.yaml

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Merge pull request #290 from ceph/wip-deep-scrub

task/ceph.py: deep-scrub instead of scrub
Add and use new fetch() method

The old fetch_branch() wasn't behaving properly with the ceph.com git
mirror. This method works with github.com and ceph.com. Add a couple
unit tests, and leave the old fetch_branch() in place for now, even
though nothing uses it.

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>