Add command to install stratum and its deps on a remote node

Also:
- update install-p4-tools.sh to build BMv2 and PI for Stratum, as
they need different configure options when used with Stratum
- improved build times (~4 minutes on cell machines)
- removed support for Ubuntu 14.0 and code related to old gnmi support
via sysrepo

Change-Id: Icf9cf936237e2815dee73bdc4370562f29616a23
diff --git a/tools/dev/p4vm/user-bootstrap.sh b/tools/dev/p4vm/user-bootstrap.sh
index 17d3b10..6420998 100755
--- a/tools/dev/p4vm/user-bootstrap.sh
+++ b/tools/dev/p4vm/user-bootstrap.sh
@@ -15,6 +15,7 @@
 export ONOS_ROOT=~/onos
 source ~/onos/tools/dev/bash_profile
 source ~/onos/tools/dev/p4vm/bm-commands.sh
+export BMV2_INSTALL=/usr/local
 EOF
 
 # Build and install P4 tools