`echo yes | rvm implode` no longer works. Explicitly remove RVM. (cc @havenwood)
Ensure chruby-exec parameters are shell-quoted.

- Preserve quotes in chruby-exec command parameters (closes #283).
- Fixes a bug where RUBYOPT options passed to chruby-exec are ignored.
Merge pull request #285 from havenwood/chruby-exec-parameters

Ensure chruby-exec parameters are shell-quoted.
Match comments in setup.sh to what the script actually does.
Set GEM_HOME to use RUBY_API_VERSION

See https://github.com/postmodern/chruby/issues/235#issuecomment-43148018 for
the source of the patch.
Merge branch 'master' into v1
Merge branch 'ruby-api-version' into v1