Add the serial to connection info for boot volumes

The serial parameter wasn't being added to volumes specified at
boot time. Added tests. Also cleaned up import in test_compute
to match the rest of the file.

Fixes bug 1148734

Change-Id: I05a623849680c5d0bb530fba4c4e6051d3b000aa
Don't include traceback when wrapping exceptions

The fix in fa52cb09b2270876c9d9a03106f961be6c9db834 strips tracebacks
from exceptions when returning them to the user, but it still spams
the log with a long traceback. We shouldn't be including the traceback
when we wrap the exception in the first place. Instead we just
include the message.

It also updates the error code to 409 for device in use since this
is actually a conflict.

Fix for:

  bug 1155315
  bug 1103324
  bug 1092610

Change-Id: I95019a3022eb52e0335c455009c13fe229475d03
Merge "Add the serial to connection info for boot volumes"
Merge "Don't include traceback when wrapping exceptions"
Merge remote-tracking branch 'm_src_repo/master' into build-temp