Extend "Sort" options

Sort options is currently a dropdown with two options "created date" and "updated date." We will extend this to include other sort options.

To start, we will provide an additional option called "Any date field." Selecting this option will display a list of all content types. Next to each type we will provide radio buttons showing all fields/properties on the content type that provide a date option. (This will include "created" and "updated" options.)

* A user will be able to set the sort date for each content type based upon the available options for that content type. The default will be "created date."

* Add a filter for limiting returned results based upon a relative "older than" date (ie, now, 1 day back, 1 day forward, etc.) that looks for the selected "sort" fields/properties.

Additional Notes:

* This might provide a way of extending the module to handle something like #1494834: Sort by taxonomy term relevance? in the future.
* Make sure that we provide error handling, should a field be removed from a content type after the bean is created.