libhawaiishell: Move show and hide configuration window to views

Views are the only objects that should be responsible for configuration
windows position and size, in order to do so views must now implement
these methods and create the configuration window on their own.

Issue: #128
client: Move configuration window here

Rename ConfigWindow to ConfigView, inherit from QQuickView and move
the code to the shell client.

Issue: #128
desktop: Move panel configuration view to the desktop shell

Having the configuration view code moved to the shell implementations
enables us to have a consistent user interface despite the containment
implementation.

Issue: #128
desktop: Rename panel configuration view

Use a meaningful name.

Issue: #128
desktop: Rename base configuration view

Issue: #128
libhawaiishell: Add configuration views to the shell package structure

Desktop and panel configuration views are in the shell package now.

Issue: #128
hawaii.xml: Add wl_hawaii_shell.set_config_surface

With this request we can assign the configuration role to both panel
and desktop configuration windows.

Issue: #128
server: Implement wl_hawaii_shell.set_config_surface

Issue: #128
client: Panel configuration view

Load a configuration view for panels.

Issue: #128
desktop: Implement size and alignment settings for panels

Now that the panel configuration view is created by the panel view we
can have access to the other settings such as size and alignment.

Issue: #128
desktop: No need to check the location before setting it

Cleanup.

Issue: #128
client: Exit configuration mode if the focus is lost

When the panel configuration window loses the focus we exit from
the configuration mode (resulting in the window itself being hidden).

Issue: #128