small plugin change

[Dave Camp <dave ximian com>]

I changed how plugin description files are written.  Instead of lame
stripped down bonobo server files, they are now more .desktop like. 
Here is the sample plugin's description file:

[Anjuta Plugin]
Location=anjuta-sample:SampleTool
Dependencies=anjuta-docman:DocumentTool
_Name=Sample Plugin
_Description=A sample hello world plugin.

All files start with a [Anjuta Plugin] header.
Fields that begin with underscores are translated.

I've updated all the plugins in anjuta2.