Avoid this error:
```
ID: salt-master
Function: pkg.installed
Result: False
Comment: Error occurred installing package(s). Additional info follows:
errors:
- Running scope as unit run-402.scope.
Loaded plugins: ovl, ulninfo
https://repo.saltproject.io/py3/redhat/7Server/x86_64/3002/repodata/repomd.xml:
[Errno 14] HTTPS Error 404 - Not Found
Trying other mirror.
No package salt-master available.
Error: Nothing to do
```
Make the upstream salt package repository selectable, thus allowing the
use of archived salt versions (hosted in
https://archive.repo.saltproject.io), as well as custom salt versions
hosted in alternate repositories.
* Semi-automated using https://github.com/myii/ssf-formula/pull/31
* Includes:
- Update TOFS
- Use `bin/kitchen`
- Use `dist: bionic` in Travis
- Add `yamllint` and apply rules
- Use `pillars_from_files` throughout
- Replace EOL images in Kitchen & Travis
- Add `develop` images in Kitchen & Travis
* Fix (or ignore) errors shown below:
```bash
salt-formula$ yamllint -s .
./pillar.example
1:1 warning missing document start "---" (document-start)
5:23 warning truthy value should be one of [false, true] (truthy)
8:25 warning truthy value should be one of [false, true] (truthy)
11:25 warning truthy value should be one of [false, true] (truthy)
19:21 warning truthy value should be one of [false, true] (truthy)
40:89 error line too long (108 > 88 characters) (line-length)
41:89 error line too long (112 > 88 characters) (line-length)
43:89 error line too long (112 > 88 characters) (line-length)
45:89 error line too long (110 > 88 characters) (line-length)
47:89 error line too long (89 > 88 characters) (line-length)
74:27 warning truthy value should be one of [false, true] (truthy)
82:9 error wrong indentation: expected 10 but found 8 (indentation)
101:14 warning truthy value should be one of [false, true] (truthy)
102:20 warning truthy value should be one of [false, true] (truthy)
103:89 error line too long (119 > 88 characters) (line-length)
121:7 warning comment not indented like content (comments-indentation)
122:24 error syntax error: found character '%' that cannot start any token
310:89 error line too long (102 > 88 characters) (line-length)
330:89 error line too long (113 > 88 characters) (line-length)
433:1 error too many blank lines (1 > 0) (empty-lines)
./salt/osmap.yaml
4:2 error syntax error: found character '%' that cannot start any token
6:89 error line too long (93 > 88 characters) (line-length)
22:89 error line too long (137 > 88 characters) (line-length)
23:89 error line too long (134 > 88 characters) (line-length)
33:89 error line too long (149 > 88 characters) (line-length)
34:89 error line too long (146 > 88 characters) (line-length)
./salt/osfamilymap.yaml
4:2 error syntax error: found character '%' that cannot start any token
6:89 error line too long (94 > 88 characters) (line-length)
24:89 error line too long (149 > 88 characters) (line-length)
25:89 error line too long (146 > 88 characters) (line-length)
39:89 error line too long (105 > 88 characters) (line-length)
40:89 error line too long (127 > 88 characters) (line-length)
56:89 error line too long (101 > 88 characters) (line-length)
./salt/ospyvermap.yaml
4:1 warning missing document start "---" (document-start)
./salt/defaults.yaml
3:1 warning missing document start "---" (document-start)
7:21 warning truthy value should be one of [false, true] (truthy)
8:12 warning truthy value should be one of [false, true] (truthy)
9:23 warning truthy value should be one of [false, true] (truthy)
10:19 warning truthy value should be one of [false, true] (truthy)
14:25 warning truthy value should be one of [false, true] (truthy)
15:25 warning truthy value should be one of [false, true] (truthy)
16:27 warning truthy value should be one of [false, true] (truthy)
17:27 warning truthy value should be one of [false, true] (truthy)
39:28 warning truthy value should be one of [false, true] (truthy)
41:28 warning truthy value should be one of [false, true] (truthy)
45:24 warning truthy value should be one of [false, true] (truthy)
49:30 warning truthy value should be one of [false, true] (truthy)
54:28 warning truthy value should be one of [false, true] (truthy)
63:25 warning truthy value should be one of [false, true] (truthy)
68:15 warning truthy value should be one of [false, true] (truthy)
```
