de-hardcode adjustment type strings in autoscaling

The scaling policy adjustment types were hardcoded throughout
autoscaling.py: 'ExactCapacity', 'ChangeInCapacity', and
'PercentChangeInCapacity'. These are now constants at the module
level.

Change-Id: I0bd610e25bdba8ab13daf94b508934dca7e30c00
Parse stack_adopt_data

The patch parses the argument passed to stack_create, and validates that
it's a dictionary, preventing engine failures in the future.

Closes-Bug: #1277106
Change-Id: I88cbf933ddac5776d5ffc0151bc7a0b296048777
Add systemd notification support to heat

This mirrors work done in other OpenStack projects
to add systemd notification support to signal that
a given process is ready to accept requests.

The heat-api, heat-api-cfn, heat-engine, and
heat-api-cloudwatch processes are all covered by
a new, single, 'onready' configuration file option.

Additionally, the sample configuration file has been
updated to match.

Implements: blueprint systemd-integration

Change-Id: I90d2b915e2568a65ed9ed78923c9982e19f9c948
Signed-off-by: Lon Hohberger <lhh@redhat.com>
Merge "Add systemd notification support to heat"
Merge "de-hardcode adjustment type strings in autoscaling"
Merge "Parse stack_adopt_data"