Option for root_helper when checking namespace

Adds a configuration option to use the root helper in the ip netns list
command executed by the IP library when checking for the existence of a
namespace.  This prevents an unprivileged l3 agent from erroneously trying
to create another namespace when one already exists. This is necessary in
environments with constrained permissions on /var/run/netns via umask or
other access controls.

However, due to the overhead incurred by calling sudo every time on systems
where this restriction isn't in place, this configuration won't be desired
all of the time. So this patch also adds a sanity check that reports back
whether or not the root_helper is required for a deployment.

DocImpact

Closes-Bug: #1348812
Closes-Bug: #1311804
Change-Id: If7560161de3be6066af0d9866e6b5cd7c7247c33
Set type=internal as part of port creation

When creating an internal device with ovs-vsctl, the 'set'
operation must occur as part of the transaction that creates the
port, otherwise the device creation will fail and an ofport will
not be assigned.

Change-Id: I30ecb920ee1c64d25b5e7eed69e92bd71caac435
Merge "Set type=internal as part of port creation"
Merge "Option for root_helper when checking namespace"