Modify stack_name regular expression in Orchestration API
Modify stack_name regular expression in Orchestration API

The stack_name in request must match some regular expression, but
the code implementation and document description is inconsistent.

Change-Id: I02c09d2624253d9ce19735dbe745ff4d3321332d
Closes-Bug: #1671126

openstack/heat,noironetworks/heat,noironetworks/heat,openstack/heat