Add setup guide for Barefoot Tofino + Stratum + ONOS (#280)
Add setup guide for Barefoot Tofino + Stratum + ONOS (#280)

* Add setup guide for Barefoot Tofino + Stratum + ONOS

* Adapted ONOS+Stratum+Tofino guide to mention pre-built ONL

* Include PR feedback for Tofino+Stratum+ONOS install guide

* Adds explanation for selecting pipeconf in Stratum+ONOS+Barefoot install guide

* Add explanation on how to enter SDE shell for Stratum+Stratum+Barefoot guide
stratum/stratum,stratum/stratum,stratum/stratum,stratum/stratum,stratum/stratum,stratum/stratum