envy theme to implement rbenv version promt
diff --git a/themes/base.theme.bash b/themes/base.theme.bash
index 05db36e..58efe11 100644
--- a/themes/base.theme.bash
+++ b/themes/base.theme.bash
@@ -24,6 +24,9 @@
 VIRTUALENV_THEME_PROMPT_PREFIX=' |'
 VIRTUALENV_THEME_PROMPT_SUFFIX='|'
 
+RBENV_THEME_PROMPT_PREFIX=' |'
+RBENV_THEME_PROMPT_SUFFIX='|'
+
 function scm {
   if [[ -d .git ]]; then SCM=$SCM_GIT
   elif [[ -n "$(git symbolic-ref HEAD 2> /dev/null)" ]]; then SCM=$SCM_GIT
@@ -113,6 +116,13 @@
   fi
 }
 
+function rbenv_version_prompt {
+  if which rbenv &> /dev/null; then
+    rbenv=$(rbenv global) || return
+    echo -e "$RBENV_THEME_PROMPT_PREFIX$rbenv$RBENV_THEME_PROMPT_SUFFIX"
+  fi
+}
+
 function virtualenv_prompt {
   if which virtualenv &> /dev/null; then
     virtualenv=$([ ! -z "$VIRTUAL_ENV" ] && echo "`basename $VIRTUAL_ENV`") || return