Define workflow in yaml syntax

Define workflows like this.

```yaml
workflows:
  question:
    roles:
      - step1: role:admin
  incident:
    roles:
      - step1: role:op1
      - step2: role:op2
```

It means two workflows.

The first workflow is named question,it's created by anyone and approved by role admin.
The second workflow is named incident, it's created by anyone ,then will be approved through step 1 to step n(this n is 2).