This adds LDAP support to the Docker image. All parameters are specified
using environment variables named following the convention in the
configuration files themselves.
This change allows Docker users to set the server URL by setting the
SERVER_URL environment variable. This is done in the same way as the
database and mail settings.
The Dockerfile now includes the php5-curl package, which is needed to
satisfy a missing dependency.
The docker/app_start.patch was updated to match changes to the source
code.
Brady Wetherington