Merge branch 'hotfix/1.22.4' into stable
manually reverted using mirror site. and use https protocols
use http, because http://ftp.ruby-lang.org is deliveried by fastly
rename hostname, ftp.ruby-lang.org is used by ftp protocol too.
Merge pull request #2198 from hsbt/revert-using-mirror

Manually reverted using mirror site. and use CDN serves.
allow easy defining multiple fallbacks for ruby, update #2198
1.22.5
Merge branch 'master' into hotfix/1.22.5
Merge branch 'hotfix/1.22.5'
add a patch to compile ruby-2.0.0-p247 on synology, fix #2184