Use PSR-0 autoloader class from Composer.
nethserver-httpd-admin.spec: build with plain .spec file. Refs #2812

Source tags adhere to
http://fedoraproject.org/wiki/Packaging:SourceURL#Github

Obsolete nethserver-nethgui package
FontAwesome included from GitHub official repository. Refs #2783
Include external packages documentation
Include PHP, JS Mustache libraries for Notification module.
CSS: updated for new Nethgui Notification module output.
Updated dependencies for Nethgui 1.6.0. Refs #2820
Use nethgui testing branch b2819
Fix Symfony Process directory structure to reflect PSR-0 namespace.
Merge branch 'b2820' Refs #2820

Embed Nethgui 1.6.0 into httpd-admin RPM
Updated Nethgui to 1.6 pre-release commithash.