update plugin management

plugins/available/ruby.plugin.bash

@@ -4,7 +4,7 @@ about-plugin 'adds "remove_gem" function'
 function remove_gem {
   about 'removes installed gem'
   param '1: installed gem name'
-  group ruby
+  group 'ruby'
 
   gem list | grep $1 | awk '{ print $1; }' | xargs sudo gem uninstall
 }