I've just attempted to install foreman on CentOS 7, however the installer is logging:

 Execution of '/usr/bin/yum -d 0 -e 0 -y list centos-release-SCL' returned 1: Error: No matching Packages to list
 /Stage[main]/Foreman::Install::Repos::Extra/Package[centos-release-SCL]/ensure: change from absent to present failed: Execution of '/usr/bin/yum -d 0 -e 0 -y list centos-release-SCL' returned 1: Error: No matching Packages to list

centos-release-SCL does not currently exist for CentOS (and will likely not exist for the foreseeable future) - the individual packages that foreman needs are available from http://projects.theforeman.org/projects/foreman/issues/new

Could this dependency be removed and replaced with the individual release files, i.e.:
yum install https://www.softwarecollections.org/en/scls/rhscl/ruby193/epel-7-x86_64/download/rhscl-ruby193-epel-7-x86_64.noarch.rpm