Check that user has provided wf_input in wf that needs it is absent in cron-triggers

[Anastasia Kuznetsova]

Steps to reproduce:
1. Create workflow definition:
version: '2.0'

wf:
  type: direct
  input:
   - var
  tasks:
    hello:
      action: std.echo output="<% $.var %>
      wait-before: 1
      publish:
        result: <% $.hello %>
2. execution "mistral workflow-create <def.yaml>"
3. execute "mistral execution-create wf"
4. Be sure that following error appears:
Invalid input [name=wf, class=WorkflowSpec, missing=[u'var']]
5. execute "mistral cron-trigger-create trigger wf --pattern '* * * * *' "

Observed result:
Cron-trigger was successfully created

Expected result:
The same error like in case of execution creation

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/185334

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/185334
Committed: https://git.openstack.org/cgit/stackforge/mistral/commit/?id=2761222195ed45d564f05fb432bf844d43750274
Submitter: Jenkins
Branch: master

commit 2761222195ed45d564f05fb432bf844d43750274
Author: Nikolay Mahotkin <email address hidden>
Date: Mon May 25 12:02:45 2015 +0300

    Adding input validation to cron-trigger creation

    Closes-Bug: #1449519

    Change-Id: Ic4542c24bf6b218bd42f50df027dba5e3ed732ac