Fixes issue 34 (update a ResourceClass flavor) and 43 (add max_vms attribute)

https://github.com/tuskar/tuskar/issues/34
https://github.com/tuskar/tuskar/issues/43
Merge pull request #51 from marios/Issue43_max_vms_Issue34_update_flavor

Fixes issue 34 (update a ResourceClass flavor) and 43 (add max_vms attri...