[notes plugin] make tabs DnDable

[Liviu Andronic]

Hello everyone,

Recently I started to use the Notes Plugin more often. Currently, I am
using 8 different tabs. The order of importance, however, varies
periodically and I'd like to be able to drag and drop, for example,
the 8th tab at the beginning of the list. Would it be possible to make
Notes make use of GTK+ 2.10 for the Tab DnD features?

Regards,
Liviu