Update test app to match new app folder structure.
Updated base url parsing to account for app's folder structure changes.
Start implementing checkbox widget.

Basic features and attributes are working, next up is making
checked property smarter.
Expand logic to detect checked.

Since value is a primitive attribute, re-using it for checked/selected
state is a bit of a bad idea. This will probably lead to refactoring in
selectbox and radio as well.
Convert value to selected in SelectBox.

Having consistency between checkbox, select, and radio is more important
than keeping the code stable at this point.
Convert Radio to use selected instead of value.

Having consistency between components is important at this stage,
and will be important later as well. Value is harder to use as it over
laps with checkbox values.
Unset attribute instead of exclude it.
Update doc blocks and coding standards.
Update doc blocks.
Make association names not retain plugins.

Creating associations in plugins should not retain aliases like
'Photos.Photos'. Instead the plugin segment should be dropped and the
association should just be called 'Photos'. This keeps behavior
consistent with previous releases and avoids annoying problems when
trying to contain() association names with `.` in them.
Make association property() exclude plugin names.

When creating association names that include plugin names we should omit
the plugin name from the hydrated dataset. Instead of 'contacts.users',
we should just get 'users' as an example.
Use 'val' instead of 'selected'.

Selected does not map well onto input types like text or hidden. Using
val lets us not shadow the value attribute, and also mirrors jQuery so
the concept shouldn't be foreign to developers.
Merge pull request #2647 from markstory/3.0-checkbox-widget

3.0 checkbox widget
Merge pull request #2648 from cakephp/3.0-plugin-associations

3.0 - fix plugin associations
Merge pull request #2646 from ADmad/3.0-app-structure-2

3.0 app structure 2