$ curl -L get.rvm.io | bash -s stable
でインストールしようとすると、
curl: (60) SSL certificate problem: Invalid certificate chain
More details here: http://curl.haxx.se/docs/sslcerts.html
curl performs SSL certificate verification by default, using a "bundle"
of Certificate Authority (CA) public keys (CA certs). If the default
bundle file isn't adequate, you can specify an alternate file
using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
the bundle, the certificate verification probably failed due to a
problem with the certificate (it might be expired, or the name might
not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
the -k (or --insecure) option.
と怒られる。調べた結果、
[curlのssl証明書エラーが出た時の対処法]（http://origami-works.com/2014/05/10/homebrew）
を参考に、設定ファイルを作成
$ echo insecure >> ~/.curlrc
すると、インストールに成功する。