Updated button widget to 1.1

* Moved most fields into sections to make the form a little more manageable.
* Added !important to button text color to prevent theme CSS from overwriting this color.
* Added title and onclick fields.

git-svn-id: https://plugins.svn.wordpress.org/so-button-widget/trunk@921108 b8457f37-d9ea-0310-8a92-e5e31aec5664