Update (most) themes to use new ${ruby_version_prompt} variable.
diff --git a/themes/pete/pete.theme.bash b/themes/pete/pete.theme.bash
index 7b6702c..cda451e 100644
--- a/themes/pete/pete.theme.bash
+++ b/themes/pete/pete.theme.bash
@@ -5,7 +5,7 @@
   history -a
   history -c
   history -r
-  PS1="(\t) $(scm_char) [$blue\u$reset_color@$green\H$reset_color] $yellow\w${reset_color}$(scm_prompt_info)$(rvm_version_prompt) $reset_color "
+  PS1="(\t) $(scm_char) [$blue\u$reset_color@$green\H$reset_color] $yellow\w${reset_color}$(scm_prompt_info)$(ruby_version_prompt) $reset_color "
   PS2='> '
   PS4='+ '
 }