Resolve merge conflict
LDAP: move PHP LDAP functions calls to an LDAP Wrapper for better isolation and mock testing
LDAP: move is_resource check to ldap wrapper to make it mockable
LDAP: establish wrapper interface to allow proper mocking
LDAP: add phpdoc
LDAP: use wrapper,  not direct function call
LDAP: don't check var type when you can specify the type in the parameter list
Whitespaces
LDAP: make Access be a dependency to the user and group backend instead of inheriting it.
LDAP: get rid of some PHP Warnings
LDAP: simple tests for the user backend
LDAP: coding style
LDAP: don't throw exceptions in the wrapper, errors are handled in the code. nevertheless, log unexpected errors