Remove Redundant Admin-Login-Related Code

[artntek]

See Issue #1694

The PR for the above issue (#1824) was focused on getting the admin login working. There is some subsequent cleanup that should be done, now it has been merged, to get rid of old code that is no longer used.

Cleanup @todo:

• tabs to spaces and format all - ideally as a separate PR - ONLY whitespace and reformatting cleanup from PR #1826 ("Reworking Admin Login Not to use Old Metacat api") #1838
• Remove unused leftovers from ldap/file auth:
  • lib/admin/auth-configuration.jsp
  • src/edu/ucsb/nceas/metacat/admin/AuthAdmin.java
• Remove AuthInterface and its implementations. We only need group info now (for legacy reasons)
• Remove old session management - SessionService and friends
• Lower priority: clean up unused parts of admin.js and admin.css