New feature as well as bug-fix changes.

(1) Created admin folder and admin/index.php, which
currently just has the ability for an admin to log in as another user
for troubleshooting reasons.  Potentially also for a residency director to see how residents are doing.

(2) Updated INSTALL to include comments on how to create an
administrative user through loginmember table.  (Also drew the
loginmember table
using Marc's method).

(3) Changed the config dist file formats and UpdateExam code to reflect
new RISName/RISDatabase variable use.

(4) Removed the Word Cloud link from login_success.php because, well,
that feature doesn't exist yet.