Add service tag section to HACKING.rst

This commit just adds a section to HACKING.rst explaining how to use
service tags.

Part of bp add-service-tags

Change-Id: I9724cec8e2009e9c2eb2d75d9254c2b5f10e7a85
Remove Whitebox tests

This commit removes the whitebox tests from tempest. The proper place
for this type of testing is in nova unit tests not in tempest.

Fixes bug 1222852

Change-Id: I0fac7b030c51985f9d6d93129bf9bab75c18cd11
Merge "Add service tag section to HACKING.rst"
Merge "Remove Whitebox tests"