Convert Auth classed to namespace, PSR2

Remove class/auth, change Xoops_Auth* classes to namespace Xoops\Auth, make Xoops_Auth abstract. 

Remove references to LDAPv2 (obsolete since 2003,) remove clumsy conversions to and from UTF-8 since XOOPS and LDAPv3 are UTF-8 based.
Merge pull request #122 from geekwright/master

Convert Auth classed to namespace, PSR2