Add src/README.md placeholder to prevent inheritence of the
base layer's readme file in the built charm.
Use the official charms.openstack repo in test-requirements.txt.
Use official designate charm location in the Amulet tests.
Remove upload-and-publish so as not to encourage out-of-band
pushing and publishing. That is handled by CI.
Remove legacy Makefile.
Rename Amulet test files and drop Icehouse on the Trusty target.
Update tox.ini for Amulet environment variables.
Update metadata.yaml, removing EOL release and adding tags.
Fix apt_pkg mock
Disable py27 unit tests
Change-Id: I5220b73eb41e42cb03e6dac27525140fb21ca449