new add resource UI

[Marco Martin]

Hi all,

the architecture of the add resource ui has been completely redone, to give 
the ability to get back after having selected the widgets category (the two 
things were implemented in a way *that* different ;)

ui wise it should look almost the same modulo some minor changes either due to 
the architectural change or from the fact that now is using a sliding panel 
looking thing that uses (almost) the same api of Harmattan Sheet qml 
component.
as a sideeffect 1 another thing that will make easier to port harmattan 
applications, side effect 2 when it's opening together the keyboard (new 
activity ui for instance) the resulting animation looks gorgeous ;)
another thing, it should make easier to change the ui to chose the categories, 
doing a tabbar for instance should be quite easy now (still think that doesn't 
scale well ;)

so, try it, there may be some regressions, hopefully not many.

Cheers,
Marco Martin