Add prefix matching for policy version

Add prefix matching for policy version

Re-introduced regular expressions to match policy version
so that the policy version found in the metadata, which is just
the major number, can be matched with a policy's version, which
is of the form, major.minor.patch.
Simplified equals() test, as we already know "text!=null".
Added filterPrefixPred() and modified policy filter to use it when
matching versions, as it is simpler to use when matching a version
prefix.
Also added tests to PfObjectFilterTest to test each of the XxxPred()
methods.

Change-Id: I0734873f701a539e883fe25b8eecfdde60cc8b6d
Issue-ID: POLICY-1542
Signed-off-by: Jim Hahn <jrh3@att.com>