Merge branch 'hotfix/1.21.8'
improved detection of zsh+version, zsh 5.0.0 is ok, update #2026
Script no longer crashes when zsh exists but ZSH_VERSION unset or null
Merge pull request #2027 from ischwabacher/patch-1

fix displaying Zsh warnings for "bad" `ZSH_VERSION`s
clean posix check when running rvm function
Merge branch 'master' of github.com:wayneeseguin/rvm
add rubygems-2.0.5.tgz md5
make zsh version check original PATH, update #2029
1.21.9
Merge branch 'master' into hotfix/1.21.9
Merge branch 'hotfix/1.21.9' into stable