Add collection count to stack list

Add an optional parameter ``with_count`` to the stack_list API to
allow the inclusion of the collection count in the body of the response

When passing the parameter, the response looks like:
{
  'stacks': [...],
  'count': 42
}

blueprint: count-stacks
Change-Id: I560cfff9d327db9b325e7cf4786bd2fcd71d47b2
Add SupportStatus class for resources

SupportStatus class has following attributes:
- status (SUPPORTED, DEPRECATED, etc. All allowed support
statuses are defined)
- message (property for providing some information about status)
- version (when resource came into specific support status)

By default support status of each resource is SUPPORTED.

Support status added to Resource class as a static attribute.

Implements bp resource-support-status

Change-Id: Ib3aacdb0f28b09ebeecfc3f13cf22587f8d57f03
Fix error in Trove Instance schema definition

Change-Id: I79d0f0318a161b4666ea149ba0691bd6dfe877f2
Merge "Fix error in Trove Instance schema definition"
Merge "Add SupportStatus class for resources"
Merge "Add collection count to stack list"