Allow Panelizer Bundles To Use Panel Page's Content/Layouts as Default

Here is a patch which subsumes the work in #1822136: "Select Allowed Layout" option in Panelizer is not respected in IPE. Page Manager defaults are used instead., but it provides the following things:

1.) It adds an option to the Panelizer "Allowed Content" screen to let the user decide if that bundle will use "Default" content types and layouts. The default here is OFF as to not break existing implementations and to make this optional functionality.

2.) It hooks into panelizer_panels_cache_get() to only set "custom" content types and layouts if the default is OFF. If the user has chosen it to be on, it just uses the global settings.

A few things that are probably still needed:

1.) I only tested this with the IPE and its possible the backend uses a different method of determing allowed content and layout sets.

2.) I think the language needs to be cleaned up a bit to be clearer to the end user so they know what they are selecting when they say defualt

3.) The interface might need some work since adding a checkbox to the vertical tabs may not be ideal. However, since #1148950: Applying #states to a vertical tab does not update the vertical tabs menu is not yet fixed we cannot do something fancy like #states and I don't know if making a custom UI just for this little tweak is required.

Here is an update to the patch to separate out the options for default content and default layout. This now exposes both in the Panelizer settings:

Here is a re-roll of #4 based on the feedback in #3. Adding a #states element is probably not possible right now due to #1148950: Applying #states to a vertical tab does not update the vertical tabs menu, #994360: #states cannot check/uncheck checkboxes elements, but this patch will properly set the disabled properties of the layout or content elements (using the same logic as panels_common_settings does) depending on those values. You will need to do a page reload if you change the setting, but I think that is intuitive enough for this uncommonly used page.

The patch in #4 also will need, in certain cases, to include the relevant Panels layout code - ctools_include('display-layout', 'panels'). There is a problem with backend Panelizer interface when it doesn't include all the layout code and currently dies as per #1828684: Fatal error: Call to undefined function panels_get_layouts()

Moving this back to needs review since the trouble we were seeing was independent and fixed with this patch #1828684: Fatal error: Call to undefined function panels_get_layouts()

Here is a quick re-roll to work against the latest dev.