Revert "Added $categories in to slim.before.despatch hook Fixed bug in logging out admin user."

This reverts commit 77c18f36ea0158fc72079818b2f4dc7ee8240c8b.
Added ircmaxell's password_compat lib as a dependency to ensure more secure password hashing with a nod to future site wide user management/login.
As a result, minimum PHP version has moved to 5.3.7
Altered 'pass' column in users table to be a 255 varchar to cater for future password defaults in PHP
Merge user
Updated README and added new sql dump to include altered 'pass' column varchar length