jQuery Mobile: Merge CSS with theme CSS

- Doing this prevents markup changes in the header between v3.0 and 3.1
- Fix missing Sass compiler directives for Base and Wet themes
- Collapse base64 encoding to single task
- Rename CSS files to SCSS
- Double ! so jQuery license header isn't stripped
jQuery Mobile: Update demos after merging CSS

Extra link is no longer required now that the CSS is included in theme
CSS files
Merge pull request #1235 from nschonni/merge-jquery-mobile-css

jQuery Mobile: Merge CSS with theme CSS