fabric: Add protocol version field

Allow providers to extend a protocol in a backward
compatible manner by adding a protocol version field.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
usnic: add reliable message support
progression and reliability in SW for now, will move to HW/FW later

Signed-off-by: Reese Faucette <rfaucett@cisco.com>
Merge pull request #390 from shefty/master

fabric: Add protocol version field
Updated nroff-generated man pages
Merge pull request #396 from rfaucett/pr/usnic_msg

usnic: add reliable message support