fix merge conflicts
add a flag for config_drive_format, default to iso9660
Merge pull request #385 from rackerjoe/v4.1.5rc

Merged automatically by jenkins after successful build test
Make scheduler_host_subset_size configurable.

Default value 1 is nova default.
Merge pull request #387 from rackerjoe/v4.1.5rc

Merged automatically by jenkins after successful build test