[sugar] Merging sugar-toolkit changes from tomeu repository

[Marco Pesenti Gritti]

I went through the patches to figure out how to go about review and
merging. The changes can be summarized as:

1 Palette improvements.
2 Accell support.
3 Add favorite property to the activity registry.

My feeling is that 1 and 2 will require a careful review and possibly
non trivial changes to be merged. 3 is pretty simple but depends on
changes in the sugar shell service.

Let's meet tomorrow morning as planned and decide how to proceed.

Marco