Fix test_assign_vm to be discovered by nose testrunner
Fix test_assign_vm to be discovered by nose testrunner

the nosetests runner will not discover tests unless the tests start with
the test_ prefix. When wrapping by the log_test_exceptions method the
name of the method changes and is not test_ anymore causing the runner
to skip the test. Included the __doc__ string as well so the runner can
report results correctly.

Signed-off-by: Prasanna Santhanam <82219615980488abd2acc1a3d71cfb58f0b2b8b6@apache.org>

wido/cloudstack,wido/cloudstack,resmo/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,DaanHoogland/cloudstack,resmo/cloudstack,DaanHoogland/cloudstack,wido/cloudstack,resmo/cloudstack,resmo/cloudstack,GabrielBrascher/cloudstack,jcshen007/cloudstack,resmo/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,wido/cloudstack,wido/cloudstack,wido/cloudstack,resmo/cloudstack,GabrielBrascher/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,wido/cloudstack,DaanHoogland/cloudstack,resmo/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,DaanHoogland/cloudstack