This patch implments the ovn-nbctl API for the Logical_Switch,
Logical_Switch_Port, and DHCP_Options commands. Additional patches
will implement logical router and load balancer functionality.
As a convenience, the add/list/get commands return a special
read-only version of an ovs.db.idl.Row object called a RowView.
This object can be compared to a Row for equality and hashing. This
saves having to return uuids and then look them up. This behavior
differs from the Open_vSwitch schema implementation. This wrapper
serves both to keep people from modifying returned values outside of
a transaction and as an interface for any future backend to implement.
In addition, an ovs virtual environment fixture based on ovs-sandbox
is added to set up a sandboxed ovs/ovn install for running functional
tests.
Change-Id: I93689158467ff73a1b02588510d168b50ed6292a
4bde2d5237