Use datatables for the api list so it's consistent with the other lists.
Allow the API backend configuration items to be reordered.

This ordering can affect the URL matching order of different APIs. This
fixes https://github.com/NREL/api-umbrella/issues/21

This also improves the progress indicator on all DataTables so the
loading progress is more obvious on longer tables.
Increase the number of rows displayed by default in some of the tables.

This affects the admin list, api user list, and apis list.
Fix loader icon so that it shows up on first load.