Make name an abstract property and omit _name

Return None instead of raising an exception to get around Python's
syntactic restrictions on anonymous functions.

Signed-off-by: mulhern <amulhern@redhat.com>
Make reads property a bit more succinct.

Signed-off-by: mulhern <amulhern@redhat.com>
Change _labelstrRegex to a more concisely defined abstract property.

Change its name to be more consistent with property names.

Signed-off-by: mulhern <amulhern@redhat.com>
Change defaultLabel to a more concisely defined abstract property.

Change its name to default_label to be more consistent w/ property names.

Only used in tests, which are updated.

Signed-off-by: mulhern <amulhern@redhat.com>
Change labelApp to a more concisely defined abstract property

Change its name to label_app to be more consistent w/ property names.

Make fslabel classes into singleton objects.

Signed-off-by: mulhern <amulhern@redhat.com>