Fix requirements checks for ruby module

Load any ruby version manager before checking the availability of ruby
command.

modules/ruby/init.zsh

@@ -5,11 +5,6 @@
 # Authors: Sorin Ionescu <sorin.ionescu@gmail.com>
 #
 
-# Return if requirements are not found.
-if (( ! $+commands[ruby] )); then
-  return 1
-fi
-
 # Load RVM into the shell session.
 if [[ -s "$HOME/.rvm/scripts/rvm" ]]; then
   # Unset AUTO_NAME_DIRS since auto adding variable-stored paths to ~ list
@@ -36,6 +31,11 @@ else
   fi
 fi
 
+# Return if requirements are not found.
+if (( ! $+commands[ruby] )); then
+  return 1
+fi
+
 #
 # Aliases
 #