Adding tunnel ipv4 src/dst flow-base model augmentations

Augments the high-level md-sal flow-base models to
support flow based tunnels rather then port based tunnels
only which is ovsdb specific, thus making a more generic
TEP implementation.

Output of tests and ovs integration is posted here:
https://gist.github.com/22f0749bba00df1a3cf6

Change-Id: Ie79f34db238a79eba5b05a0262bf91c043dd82d2
Signed-off-by: Brent Salisbury <brent.salisbury@gmail.com>
Merge "Adding tunnel ipv4 src/dst flow-base model augmentations"