Using xmllint to convert/parse old agent.conf t ocontrail-vrouter-agent.conf(ini file).

Change-Id: I7a0c4f90b82da42a0440ff04562b142f3c0dcfb9
Merge "Using xmllint to convert/parse old agent.conf t ocontrail-vrouter-agent.conf(ini file)." into R1.10