* Semi-automated using `ssf-formula` (v0.5.0)
* Fix errors shown below:

```bash
ufw-formula$ $(grep "\- yamllint" .travis.yml | sed -e "s:^\s\+-\s\(.*\):\1:")
pillar.example
  1:1       warning  missing document start "---"  (document-start)
  3:12      warning  truthy value should be one of [false, true]  (truthy)
  7:11      warning  truthy value should be one of [false, true]  (truthy)
  12:22     warning  truthy value should be one of [false, true]  (truthy)
  64:13     warning  truthy value should be one of [false, true]  (truthy)
  69:13     warning  truthy value should be one of [false, true]  (truthy)
  77:13     warning  truthy value should be one of [false, true]  (truthy)
  84:14     warning  truthy value should be one of [false, true]  (truthy)
  101:16    warning  truthy value should be one of [false, true]  (truthy)
  106:14    warning  truthy value should be one of [false, true]  (truthy)
  110:13    warning  truthy value should be one of [false, true]  (truthy)

test/salt/pillar/default.sls
  1:1       warning  missing document start "---"  (document-start)
  2:12      warning  truthy value should be one of [false, true]  (truthy)
  9:14      warning  truthy value should be one of [false, true]  (truthy)
  12:13     warning  truthy value should be one of [false, true]  (truthy)
  15:13     warning  truthy value should be one of [false, true]  (truthy)
  19:13     warning  truthy value should be one of [false, true]  (truthy)
  25:14     warning  truthy value should be one of [false, true]  (truthy)
  29:13     warning  truthy value should be one of [false, true]  (truthy)
```