Added min-width to (bootstrap) radio buttons to prettify settings

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31382

The Yes/No and Show/Hide toggle buttons have different widths and look ugly. This gives the buttons a min-width, making them the same width on at least default English and languages that don't use 20char words for these.

![tooltips](https://f.cloud.github.com/assets/744259/765133/1dd5a424-e822-11e2-91bf-ab43c5b58e1e.png)

#### Testing Instructions
Go to - for instance - the config view for articles:
administrator/index.php?option=com_config&view=component&component=com_content

Compare the toggle options before and after this patch and be in awe!