Update ui window

Hi,

This MR attempts to move all it can be move to totem.ui file. The point is to facilitate to maintain totem-object and, I hope maybe, to make easy the split between totem-application and totem-window.

For now :

• The controls button
• The main header
• The full-screen header
• Bacon video widgets (mainly signals)
• Grilo widget

There is maybe more I don't remember.

I'm not sure if this MR can be an opportunity to improve this widgets and to split the GActionEntry between "app." and "win." for the menus. Don't hesitate to tell me.

Thanks