hob: re-designed interaction and implementation

hob: re-designed interaction and implementation

Highlights include:

* Atempted GNOME HIG compliance
* Simplified UI and interaction model
* Sorting and type to find in tree views
* Preferences dialog to modify local settings
* Dialog to add and remove layers
* Search in packages list
* Save/Load image recipes

The build model has been changed, hob will attempt to build all dependent
packages of an image and then use the buildFile server method to build the
created image.

Signed-off-by: Joshua Lock <josh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>