[SDFAB-1197] First stab to update ONOS to py3

Update has been performed only on the scripts and the
executables strictly necessary for the following use cases:

- Build (including Intellij)
- Tests (including Intellij)
- Docker build (including dev and yourkit)
- Upload snapshot (including local)
- Release

Finally, fix the ability to run ONOS using onos-local targets,
stc and docker stc (aka up4 stc env). Last but not least, updated
the azul image to a newer one which exports also the PYTHONENCODING

Change-Id: Ie96f3a9c76dbba83b1fc3896a372f1045d3d7ccc
diff --git a/tools/build/bazel/onos_app_tools.py b/tools/build/bazel/onos_app_tools.py
index 9979ab5..43cab17 100755
--- a/tools/build/bazel/onos_app_tools.py
+++ b/tools/build/bazel/onos_app_tools.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
  Copyright 2018-present Open Networking Foundation
 
@@ -207,7 +207,7 @@
         values['category'] = options.category
         values['url'] = options.url
     elif options.write_app:
-        sys.stderr.write('ERROR: Feature Name, Version, and Title are required\n')
+        sys.stderr.write('ERROR: App Name, Origin, Category and URL are required\n')
         sys.stderr.flush()
         sys.exit(1)