vmware: Reuse existing StorageError class

Change-Id: If3061b8ebc5ca50a03428b67a0b941f07a314d04
vmware: Use exc_info when logging exceptions

There were several instances where we were logging exceptions as a
string, but from the context a full stack trace was intended. This
change updates these to use exc_info, which logs the exception with a
full stack trace.

Change-Id: I93ac0208c3643ac90ffb36e50ad59f49c66ad88b
make lifecycle event logs more clear

Instead of logging integers in a cryptic way, log the human
readable strings for VM event state transitions. Also use the
existing instance_uuid port of the logger instead of putting that
separately into our log message.

Change-Id: I96c39ad4494aa06a8dd5bd942c669a16836a8b9c
Merge "vmware: Reuse existing StorageError class"
Merge "vmware: Use exc_info when logging exceptions"
Merge "make lifecycle event logs more clear"