7.x 4.x admin interface phase2

Multiple improvements and additions to the Springboard administrative user experience. Most notably:

* Restoring system paths of administrative pages to admin/* rather than springboard/*
* Aliasing of administrative pages to corresponding springboard/* paths.
* Redirecting of appropriate users to the corresponding springboard/* path for appropriate administrative pages.
* New administrative pages, reports, and permissioning as needed.
* Addition of "Asset Library" administrative area which aids in managing a configurable group of content types.