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>