Bug 1953 - fix of this bugs impact on OFP

- fixed errors where Ipv4Prefix was instantiated without mask
- fixed errors where Ipv4Address was instantiated using mask
- fixed failing tests

(cherry picked from commit 5babf6a243fa671276b4bb9c04d7a1e8f3b607e3)
Change-Id: I3a9270fc75128ab5fa7ee12bf92ad9a1cb324fc0
Signed-off-by: Martin Bobak <mbobak@cisco.com>
Signed-off-by: Michal Rehak <mirehak@cisco.com>