Adding a Karaf distribution for TTP

Added as part of getting TTP ready for Karaf in Helium. This loads the TTP
model, the MD-SAL, RESTCONF, and the apidoc explorer. After running karaf:

   ./target/assembly/bin/karaf

browse to:

   http://localhost:8181/apidoc/explorer/index.html

and you will see the onf-ttp module loaded.

Change-Id: I5f4e9fab04062da6f6c3af117e21e25900a59e71
Signed-off-by: Colin Dixon <colin@colindixon.com>