Fixed P4 tools build script for Ubuntu 14

+ bumped version of p4runtime and BMv2
+ minor update to bmv2.py

Change-Id: I7784b075b2e6015bb3eef1286011968303b66129
diff --git a/protocols/p4runtime/proto/BUCK b/protocols/p4runtime/proto/BUCK
index f7ef33e..33c46f4 100644
--- a/protocols/p4runtime/proto/BUCK
+++ b/protocols/p4runtime/proto/BUCK
@@ -5,7 +5,7 @@
 P4RT_PROTOC_VER = '3.0.2'
 P4RT_GRPC_VER = '1.3.0'
 
-PI_COMMIT = 'f110570ca0c8ddc5feaf5028b08a0f477ceb4eea'
+PI_COMMIT = '8051d54c9c3415ca800db232a226189fd17ad60a'
 PI_BASEURL = 'https://github.com/p4lang/PI.git'
 
 # Wondering which .proto files to build? Check p4runtime's Makefile: