Merge branch 'release/1.20.0'
fix detecting libyaml-devel on fedora, handle unknown epel version, simplify loading centos like requirements
Merge branch 'hotfix/1.20.1'
fix rvm_src_path for macports
fix extracting macports
make sure port is in PATH
fix detecting if rvm is a shell function in installer
do not try to install epel if libyaml-devel is already installed on centos like systems
improved detection of output for curl in installer
1.20.2
Merge branch 'master' into hotfix/1.20.2
Merge branch 'hotfix/1.20.2' into stable