Make the code somewhat smaller. Disable disk failure test for master for now.

Reviewed-by: schreiberal

Testing failure on the primary node is currently disabled due to drbd problems.

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: schreiberal

- Implement colours in qa_utils.
- Print warning for cron script.

Reviewed-by: iustinp

- Test “gnt-backup export” and “gnt-backup import”.
- Move “ResolveInstanceName” to qa_utils.py.
- Fix tests for “ganeti-watcher”.
- Make instance shutdown and startup configurable.

Reviewed-by: schreiberal

Reviewed-by: iustinp