All contributions to this charm where made under Canonical
copyright; switch to Apache-2.0 license as agreed so we
can move forward with official project status.
Change-Id: Ibf6fa0c9554e852da885068c23ba06252745a14e
Xenial does not install python2 by default; ensure that python2
and minimal module dependencies are installed prior to trying
to execute any python2 based hooks.
Update amulet tests to drop shared-db relation for n-gateway.
This change also includes a resync of charm-helpers to pickup
new changes for systemd support.
Change-Id: Icef9679cd1d1c96e8aa87bcedcf9735a41af8d52
Closes-Bug: #1555422