set bytes_transffered such that it is posted to imaging service
Don't use hardcoded device name.

Fixes for: EUCA-9054
Merge branch 'master' of github.com:eucalyptus/eucalyptus-imaging-worker
Set default log level to debug
Add mkfs to sudoers file
Use /mnt/imaging as a working dir for the imager
Create key files in the /var/lib/eucalyptus-imaging-worker dir
Code reformat by PyCharm
Periodically report EXTANT status to server.
Fixes for: EUCA-9053
Merge blockdev_ops to master for volume use and state checks