[COOK-2569] Add pip default install options

With this pull request we will allow default installation options for the pip_install or pip_upgrade providers.  This will help to reduce duplication when installing/upgrading packages with common options.  Some common options might include specifying a local package repo from which to grab packages.

An example usage would look like:

```ruby
node['python']['pip']['default_install_options']['index-url'] = "http://pypi.python.org/simple"
```

This will be formatted and prepended to the `new_resource` options.  This option is the equivalent of typing:
```
--index-url http://pypi.python.org/simple
```

The default installation options will be formatted by looping over the `default_install_options` hash and for each key, value pair we will format them in the following manner:

`--#{key} #{value}`