Provide user with more information on quota fail

Provide the user with useful information when a snapshot or volume
create fails because it would cause the user to exceed available quota.
Specifically report the user's current gigabyte usage and quota
allocations.

Closes-Bug: #1235148

Change-Id: Ib4c5dbcbd172c69834c2824791af755380f38e01
Utilizes assertIsNone and assertIsNotNone

Using assertEqual/assertNotEqual to test if an element
is or is not None is too python2.4.
Our unit testing framework supports assertIsNone and assertIsNotNone
which were created for these types of tests.

Change-Id: I2e430e87dd0222b194a84f2928ad36aac26aaba6
Imported Translations from Transifex

Change-Id: I68cbee28565b1b4bd0352a4d769744cab28b71a0
Merge "Provide user with more information on quota fail"
Merge "Utilizes assertIsNone and assertIsNotNone"