Fixed issue #16, issue #17

**Fixed issue #16 so css abbreviations are expanded correctly in NetBeans 7.3 beta 2.**
The issue appeared because mime type spelling of css files (maybe others) was changed since 7.2 from 'text/x-css' to 'text/css' so default rules of html files were applied. My changes can be awkward and redundant but I tried to cover bacward compatibility and hypothetic forward compatibility.

**Fixed  issue #17 so abbreviations in *.scss, *.sass, *.less files are expanded like in *.css**
This issue is pretty close to previous one.
I've tested with .scss and .less files as I didn't find a .sass support plugin.
There can be a problem if other plugins define other mime types for the files from plugins I have used.

*As I'm not a Java programmer and I don't know Netbeans plutform. So maybe you will rewrite the code in better way.*