Fix several issues with devstack and Quantum + OVS plugin

- flag telling nova quantum manager to use DHCP is incorrect
- OVS quantum plugin no longer has default sql_connection string.
- only run quantum OVS agent is openvswitch is enabled
- add ovs-vsctl to sudoers file.

Change-Id: I1e9b3fe987b3e29d0d4f670b2d964777d9cc3e1b
diff --git a/files/sudo/nova b/files/sudo/nova
index 0a79c21..bde1519 100644
--- a/files/sudo/nova
+++ b/files/sudo/nova
@@ -41,6 +41,7 @@
                       /usr/bin/socat,                           \
                       /sbin/parted,                             \
                       /usr/sbin/dnsmasq,                        \
+                      /usr/bin/ovs-vsctl,                       \
                       /usr/sbin/arping
 
 %USER% ALL = (root) NOPASSWD: SETENV: NOVADEVCMDS