Add arguments to contrail-version so that it shows version only for the requested packages.
Then, in api server, only request it for contrail-config package. This returns much faster than listing all packages and then grepping for contrail-config

Change-Id: Iac13cb62c4e8b45c569d168de0da8f744f6b24b6
Closes-Bug: 1362371
Merge "Add arguments to contrail-version so that it shows version only for the requested packages. Then, in api server, only request it for contrail-config package. This returns much faster than listing all packages and then grepping for contrail-config"