ovs-vswitchd doesn't declare its QoS capabilities in the database yet,
so the controller has to know what they are. We can add that later.
The linux-htb QoS class has been tested to the extent that I can see that
it sets up the queues I expect when I run "tc qdisc show" and "tc class
show". I haven't tested that the effects on flows are what we expect them
to be. I am sure that there will be problems in that area that we will
have to fix.
The main purpose of the vconn code is to ship OpenFlow messages across
network connections. Over time a large number of utility functions related
to OpenFlow messages have also crept into vconn.c, but that's really
logically separate. This commit breaks those functions out into a new
file.
