Add an action after write_css to let an external plugin minify the generated CSS file.
Add filters/actions to change the datastore

Pipe the `update_option` and `get_option` call through a
`save_css_code` and `get_css_code` method.
Slug function to sanitize the CSS before saving.
Sanitize the CSS in `save_css_code`

The import functionality wouldn’t catch the sanitize otherwise.
Move the action into the sanitize function

That way the action will run even through register_setting and the
traditional way.
Merge pull request #1 from georgestephanis/filters-and-actions-additions

Filters and actions additions