Modify CSIT test files and library file of VTN Manager.
* Fixing invalid input values(inet4src, inet4dst, icmp code and icmp type) in flowfilter robot test files.
* Modified Dumpflow command in VtnMaKeywords.robot.
* Due to Bug 5587 added Tags exclude for ICMP test cases in flowfilter robot files for both OF10 and OF13.
Once bug is fixed and resolved, will remove Tags exclude and enable ICMP test cases in flowfilter robot files.
Change-Id: I7dec55e97affc0ccfb56c2104faa34b541646cee
Signed-off-by: Karthik.S <siva-karthik@hcl.com>