openflow: import and tweak

Based on work by David Nyström (meta-virtualization) and Laszlo Papp
(meta-oe).

   - Import OpenFlow 1.0 from meta-virtualization and provide an updated
     version of the recipe for the head of tree in the OpenFlow git
     repository.

   - Minor tweak in both recipes for do_install_append() spacing.

   - Update 'libssl' PACKAGECONFIG flag in both to follow the 'openssl'
     convention used elsewhere in meta-oe.

   - Create common include file for both versioned and git recipes.

Signed-off-by: Joe MacDonald <joe@deserted.net>