vtep-ctl: Add Tunnel table to vtep_ctl_table_class.

vtep-ctl: Add Tunnel table to vtep_ctl_table_class.

This is needed to create, get, set records in the Tunnel table.

(We need to add the Tunnel table's 'local' and 'remote' columns
that point to the Physical_Locator record to cache because vtep-ctl
commands like 'add-ucast-local' will try to add an entry in
Physical_Locator table based on the contents of the cache.)

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ariel Tubaltsev <atubaltsev@vmware.com>
Acked-by: Justin Pettit <jpettit@nicira.com>