Improvements to LDAP extension, with nickname support and meaningful error messages

[Yippy]

Added Nickname support, with the ability to use any search field that is set within settings. Please note That Nicknames extension must be enabled to be able to save Nicknames, placeholder will display givenname,sn as a example which is 'First Name' 'Surname' to be set as the Nickname for user profile

Added LDAP error messages for users, instead of the 'Error has occurred' html response. This will fix #48 issue.

Added Setting to allow admin's to display detail errors or not, this is a toggle in settings:

Detailed error response will display incorrect LDAP binding:

Detailed error response will display if LDAP search for account exist:

Detailed error response will display if LDAP account password is incorrect:

[Yippy]

Will also fix #39 issue.

[Yippy]

Implemented multiple LDAP domain settings, overhaul settings to display settings into sections. Added select2 to handle dropdown and multiple selection, pre-register LDAP fields options for easier usability.