Resources which go into an unknown or error state currently
raise an Error exception. There are cases where Error is too
generic to make decisions on, so 2 new exceptions have been
created:
* ResourceInError: raised when a resource goes to a status which
is known to represent an error for that resource
* ResourceUnknownStatus: raised when a resource goes to a status
which heat is not aware of. If ResourceUnknownStatus is ever raised
then this is a heat bug, since this is a status which heat is not
aware of.
Any resource which go into an in-progress state has been updated to
raise ResourceInError and ResourceUnknownStatus where appropriate.
Change-Id: Ied83b030d30b8c26d9f4a1e454c71cd30715b0ba
f0ec53626e