Allow reference conditions by name

This change allows reference with other conditions by name in
definition of a condition, something like:
   conditions:
     cd1: {equals: [{get_param: env_type}, 'prod']}
     cd2: {not: cd1}
     cd3: {equals: [{get_param: zone}, 'fujian']}
     cd4: {and: [cd1, cd3]}

Change-Id: I4fbc3839977d2d4299d65d4d56e3d41d56d07aef
Blueprint: support-conditions-function
1 file changed
tree: 29d06d106ba1b1823515d7dbf15f3c1afc1dfa66
  1. common/
  2. functional/
  3. scenario/