Add several social handlers (Personal plugin)

Hello,

someone has contribued several social handlers for fusiondirectory see :

• https://github.com/fusiondirectory/fusiondirectory-plugins/issues/29
• https://github.com/fusiondirectory/fusiondirectory-plugins/issues/30
• https://github.com/fusiondirectory/fusiondirectory-plugins/pull/31

Cheers