Merge pull request #21 from mirrorcoder/master

Add some consts
Add unittests for image resource and actions

 - Extend glance_image resource's unittests
 - Add unittests for get_info_images action
 - Add unittests for copy_g2g action
 - Fix converters unittests (import fail, pep8)
Merge pull request #23 from miarmak/image_unittests

Add unittests for image resource and actions
Add QemuImg Utils