Add option for additional php file types

To add additional file types to php, currently you have to modify the following file:

1. /usr/local/apache/conf/includes/pre_virtualhost_global.conf

And then inside that file, it depends on what version you are on.

With cPanel & WHM version 56:

1. <IfModule mod_mime.c>
2. AddType application/x-httpd-php .php .php5 .phtml .otherfile1 .otherfile2 .otherfile3
3. </IfModule>

With cPanel & WHM version 58:

1. <IfModule mod_mime.c>
2. AddType application/x-httpd-ea-php56 .php .php5 .phtm .otherfile1 .otherfile2 .otherfile3
3. </IfModule>

As a system administrator and webhost, we need a way to define those "otherfiles" in the GUI without having to continuously manually adjust the file.