adds shell glob support to file_root and pillar_root

In salts master config, I found it uncomfortable to write each included formula in file_roots one by one like so:
```
file_roots:
  base:
    - /vagrant/formulas/formula-foo/
    - /vagrant/formulas/formula-bar/
    - /vagrant/formulas/formula-baz/
    - /vagrant/formulas/formula-moare/
```
To use the `formulas` top level dir wasn sufficient, as that results in "double" namespaces depending on the formulas directory structure e.g. `formula-baz.baz.function` instead of `baz.function`.

Now one can instead simple use a shell glob:
```
file_roots:
  base:
    - /vagrant/formulas/**/
```

Also works with `pillar_roots` and the corresponding singular cli parameters of `salt-call`.

Unfortunately I wasn't able to locate a proper test case example in the current repo, if you know of a good way to test this behavior, please let me know!