Change-Id: I954e0653f3f8d0c59ae87ef6efebee8409389923

Change-Id: Ib89e69a6d2c5b9e652bfed74acbbcbcc4a7186d6

Change-Id: Ifc653a91aa82208fa4a9deba82d3f84075aa1447

Tidy pep8 errors.

Add gitreview configuration.

Drop registration of default release selector - not required.

Use default version of ceilometer charm in testing now that
relevant changes have landed.

Ensure sane default release is passed to charm superclass.

Correct behaviour for disabling services based on any of the
required states not being set.

Add xenial-pike test target.

Change-Id: Iefcdc1d4870572dae00e71e1b855fb1abf68a4e9