Ironic needs to do some capability matching that has feature parity with
Nova's capability matching. Rather than trying to re-create it
ourselves, move Nova's matching code into oslo.utils so that we make
sure it's always the same.
Also has small modifications to handle pep8 complaints in oslo.utils,
renaming the file and test names to be more generalized, and to use
oslotest instead of nova.test.
Change-Id: I3b70afdf1479b6649feac509b794d04fc5836194