Configuration processing in .ini format

Process configuration in .ini format Configuration by default is now read off /etc/contrail/ in
control-node.conf, collector.conf, qed.conf. dns.conf and vrouter.conf

agent.conf that contains some of the agent configuration in xml format still remains as is. It should also be collaped into vrouter.conf for ease of use and consistency.

contrail-status is happy in ubuntu and centos. Not able to run sanity due to unrelated changes. But changes have been sent out for review.

This pull request is for config_ini_format branch, which is a clone of the master branch. Once the review is complete, sanities pass and fab (upgrade) part is hashed out, these changes shall be merged to the master branch.