Use the library function for ruby prompt

Not everyone uses rvm and the library has already got a function for this.

themes/half-life.zsh-theme

@@ -95,4 +95,4 @@ function steeef_precmd {
 }
 add-zsh-hook precmd steeef_precmd
 
-PROMPT=$'%{$purple%}%n%{$reset_color%} in %{$limegreen%}%~%{$reset_color%}$(rvm-prompt " with%{$fg[red]%} " v g "%{$reset_color%}")$vcs_info_msg_0_%{$orange%} λ%{$reset_color%} '
+PROMPT=$'%{$purple%}%n%{$reset_color%} in %{$limegreen%}%~%{$reset_color%}$(ruby_prompt_info " with%{$fg[red]%} " v g "%{$reset_color%}")$vcs_info_msg_0_%{$orange%} λ%{$reset_color%} '