Allow salt modules to be refreshed by adding `refresh_modules: true` to a specific state.

As an example for the above feature in a more complex example:

```yaml
python-pip:
  {#
    I'm installing pip this way since I want the most up to date version
    for all distributions. This avoids trying to handle different versions
    accepting different CLI options.

    This was originally needed because the pip package installed in RHEL/CentOS 5
    was for python 2.4 and I could not find a python 2.6 package of it.
  -#}
  cmd:
    - run
    - cwd: /
    {% if grains['os'] == 'SmartOS' %}
    {#- Adapt to SmartOS's script directory #}
    - name: easy_install --script-dir=/opt/local/bin -U pip virtualenv
    {%- else %}
    - name: easy_install --script-dir=/usr/bin -U pip virtualenv
    {%- endif %}
    - require:
      {%- if grains['os'] == 'openSUSE' %}
      {#- Yes! openSuse ships xml as separate package #}
      - pkg: python-xml
      {%- endif %}
      - cmd: python-setuptools
    - reload_modules: true
```

See the last line?
If no exception occurs in this state, after it's execution, salt **will** reload it's modules.