Fix peepcode theme ruby prompt info (#5339)

The ruby prompt info was not interpolating properly. Switching to use
 ruby_prompt_info helper. This addresses the issue.

themes/peepcode.zsh-theme

@@ -41,10 +41,4 @@ PROMPT='
 %~
 ${smiley}  %{$reset_color%}'
 
-if [[ -d ~/.rvm ]] && [[ -e ~/.rvm/bin/rvm-prompt ]]; then
-    rvm_prompt='$(~/.rvm/bin/rvm-prompt)'
-else
-    rvm_prompt=''
-fi
-
-RPROMPT='%{$fg[white]%} $rvm_prompt$(git_prompt)%{$reset_color%}'
+RPROMPT='%{$fg[white]%} $(ruby_prompt_info)$(git_prompt)%{$reset_color%}'