This commit adds the configuration options related to resource limits
in the Heat project. The `max_software_configs_per_tenant`,
`max_software_deployments_per_tenant`, and `max_snapshots_per_stack`
options have been added to control the maximum limits for software
configs, software deployments, stack snapshots.
Story: 2011006
Task: 49401
Change-Id: If33a1c6f3eb9e93f586931bc5c05104439c92bf9