Enable OpenFlow 1.0, 1.1, 1.2, and 1.3 by default.

Enable OpenFlow 1.0, 1.1, 1.2, and 1.3 by default.

The Open vSwitch software switch now supports all the required features of
OpenFlow 1.0 through 1.3, with one known trivial exception[*].  Enable them
by default in ovs-vswitchd.

For now, ovs-ofctl only enables OpenFlow 1.0 by default.  This is
because ovs-ofctl implements command such as "add-flow" as raw
OpenFlow requests, but those requests have subtly different semantics
in different OpenFlow versions.  For example:

    - In OpenFlow 1.0, a "mod-flow" operation that does not find any
      existing flow to modify adds a new flow.

    - In OpenFlow 1.1, a "mod-flow" operation that does not find any
      existing flow to modify adds a new flow, but only if the
      mod-flow did not match on the flow cookie.

    - In OpenFlow 1.2 and a later, a "mod-flow" operation never adds a
      new flow.

[*] OpenFlow 1.1, but not any earlier or later version of OpenFlow,
    requires support for VLANs introduced by Ethertype 0x88a8, but Open
    vSwitch does not support this Ethertype.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Reviewed-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>