ONOS-7330 Added ONOS-P4 VM build script

Builds and OVA from scratch with the most updated tools in one command.
The build process is based on Vagrant.

Change-Id: I633d99092946f99e877f0c97631a4f99c5b1f37e
diff --git a/tools/dev/p4vm/pre-ova-cleanup.sh b/tools/dev/p4vm/pre-ova-cleanup.sh
new file mode 100755
index 0000000..17b15f3
--- /dev/null
+++ b/tools/dev/p4vm/pre-ova-cleanup.sh
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+set -xe
+
+# Delete vagrant user
+sudo userdel -r -f vagrant
+
+# Free space on disk
+cd ~/p4tools/protobuf && make clean
+cd ~/p4tools/grpc && make clean
+cd ~/p4tools/bmv2 && make clean
+cd ~/p4tools/bmv2/targets && make clean
+cd ~/p4tools/p4runtime && make clean
+rm -rf ~/p4tools/p4c/build
+
+cat /dev/null > ~/.bash_history