Update install-p4-tools.sh to use P4Runtime v1.0

Includes also various improvements to the p4vm scripts, such as:
- Choose to build VM with Ubuntu 16.04 or 18.04 (experimental)
- Allow users to specify version of protobuf and grpc to use
- Avoid building protobuf and grpc if already installed in the system
- Install Bazel 0.22

Also:
- Remove check for invalid group member weights (now PI always returns
members with weight 1)
- Re-compiled all P4 programs and fixed missing padding in controller
packet headers

Change-Id: I0e672fcebbaba63354c749f0c774af251f3cbc6c
diff --git a/tools/dev/p4vm/export-ova.sh b/tools/dev/p4vm/export-ova.sh
index 81f6d03..bc0e5c4 100755
--- a/tools/dev/p4vm/export-ova.sh
+++ b/tools/dev/p4vm/export-ova.sh
@@ -27,6 +27,7 @@
 # Remove references to the existing vagrant-built VM (if any).
 # We want to build a new one from scratch, not start an existing one.
 rm -rf .vagrant/
+vagrant box update
 vagrant up
 
 SSH_PORT=`vagrant port --guest 22`