Update Mininet VagrantBox

- Use Ubuntu 14.04 LTS
- Upgrade OVS to 2.1.0
- Note: Nasty hack to symlink ovs-controller to /usr/bin
- This can be reverted when it's reintroduced in the debian packages

Change-Id: I4ca320c361f8321a75c674c64bb5ddf37e4d803e
Signed-off-by: Dave Tucker <djt@redhat.com>
Merge "Update Mininet VagrantBox"