Add email and display name header injection support

[efeat]

Reverse-proxy-auth-plugin supports name & groups header injections but emails and display name are fetched from the LDAP server.

This fork add email and display name header injection support.
Thus we can manage authentication and user profile data with an httpd server.

What's more, using an httpd server as a reverse proxy, provides a simple solution to:

• connect to several LDAP servers (even with different structures)
• use technical users managed in the httpd server
• create an SSO plateform with other integrated applications

The original fork was made on tag 1.4.