Add schema for workflow input with default value support
Add schema for workflow input with default value support

Only add schemas. The schemas are needed for supporting something like:

my_wf:
  type: direct
  input:
    - param1
    - param2: 10

Partially Implements: blueprint mistral-default-input-values

Change-Id: I5891c5278b54e361b8818c96c771c0af9396607a

dennybaa/mistral,openstack/mistral,StackStorm/mistral,dennybaa/mistral,StackStorm/mistral,openstack/mistral