Ensure volume is deleted after build error
Ensure volume is deleted after build error

When creating a test server and the volume fails to build
a VolumeResourceBuildErrorException is raised causing a resource
leak on the testing system[1]

This change aims to remove the volume before raising the exception
to the calling test so that the system is properly cleaned up of
testing resources before exiting.

[1] http://paste.openstack.org/show/743062/

Change-Id: Ib064e4f2cb113f98da73db519d855fa892515f66

openstack/tempest,cisco-openstack/tempest,masayukig/tempest,masayukig/tempest,cisco-openstack/tempest,openstack/tempest