add a class site_config::shell for shell-related configurations
setup a /etc/profile.d configuration snippet to put /srv/leap/bin in the $PATH (#2122)

Change-Id: I0afb5232375e6c6d9f692a97243023c710265d54
Merge branch 'feature/leap_path' of /home/git/repositories/micah/leap_platform into develop
Merge branch 'develop' of git.codecoop.org:micah/leap_platform into develop