Remove Python 2.6 classifier

Heat does not support Python 2.6 anymore starting with Kilo and might
not work correctly with it, so remove the classifier.

Change-Id: Ie8239823b448cc95fdcce3afe27523cb960863d6
Deprecate HARestarter resource type

This was basically a failed experiment in High Availability. Amongst other
things - for example it is perpetually causing users to misunderstand how
it works - it relies on the paradigm of a resource just being a place to
stick code that can then go and perform operations on the stack itself
which are not defined in Heat's lifecycle model, rather than purely as a
representation of some real OpenStack resource. We later realised that this
was the cause of many of our worst headaches. Convergence will be a far
superior solution to the problems that HARestart was designed to solve.

HARestarter is an architectural dead-end, and we need to communicate that
much more clearly to users along what it actually can and cannot do.

Change-Id: I4ad9c7ae54e3f04224b780ecb24d0827951d18da
Add some unit tests for the instance group

Part of blueprint decouple-nested
Change-Id: I46c18a5545658a3a10c9eb3e9a6d1511bbe7a518
Add proper unit tests for group Tags

Part of blueprint decouple-nested
Change-Id: Ib3a561c01a32bf6a118f06cf244632aa8c8a3922
Prevent showing 'show' too early

The logic in format_resource_attributes was succeptible to a failure
when resource that has 'show' attribute and is early IN_PROGRESS has
that attribute not populated yet, returning an empty string instead.

That might happen when asking for resource-show soon enough after
stack-create, and that is what test_server_cfn_init in
heat_integrationtests effectively does.

Change-Id: I37e209042048cb4409fcd27fcf9587b594f3129b
Closes-Bug: #1401107
Merge "Remove Python 2.6 classifier"
Merge "Deprecate HARestarter resource type"
Merge "Add some unit tests for the instance group"
Merge "Add proper unit tests for group Tags"
Merge "Prevent showing 'show' too early"