Move novaclient exceptions to heat.tests.v1_1.fakes

Applying novaclient exceptions fix from commit:
9850832da563c1113e121b99d38feb21af9daa8d

"Raising nova exceptions has been moved to
heat.tests.v1_1.fakes.fake_exception since it is actually impossible
to directly create a nova exception object which works on both
novaclient 2.17 and (yet to be released) 2.18.
nova.exceptions.from_response is stable across novaclient releases
so all test exceptions are now raised using from_response."

Change-Id: I0c5e58ffdd3eb13b9a87df22f1c5e06cec972913
Closes-Bug: #1322098
Merge "Move novaclient exceptions to heat.tests.v1_1.fakes" into stable/icehouse