ovs-vswitchd: Add ability to disable in-band on a bridge

ovs-vswitchd: Add ability to disable in-band on a bridge

In-band control is always enabled when a manager is configured.  Some
applications wish to control all the flows within a bridge, and in-band
control can override that wish.  Depending on how the network is
configured, this can lead to loops as the in-band control rules try to
learn where to send traffic.

This commit adds a "disable-in-band" key to the "other_config" column of
bridge tables.  If set to "true", in-band will be disabled regardless of
manager or controller configuration.