Add RVM/cider caveats to alt. Rubies.

Formula/jruby.rb

@@ -31,6 +31,13 @@ class Jruby < Formula
     end
   end
 
+  def caveats; <<-EOS.undent
+    Consider using RVM or Cider to manage Ruby environments:
+      * RVM: http://rvm.beginrescueend.com/
+      * Cider: http://www.atmos.org/cider/intro.html
+    EOS
+  end
+
   def test
     system "jruby -e 'puts \"hello\"'"
   end

Formula/rubinius.rb

@@ -30,4 +30,11 @@ class Rubinius < Formula
 
     system "/usr/bin/ruby", "-S", "rake", "install"
   end
+
+  def caveats; <<-EOS.undent
+    Consider using RVM or Cider to manage Ruby environments:
+      * RVM: http://rvm.beginrescueend.com/
+      * Cider: http://www.atmos.org/cider/intro.html
+    EOS
+  end
 end

Formula/ruby-enterprise-edition.rb

@@ -19,6 +19,10 @@ class RubyEnterpriseEdition <Formula
   end
 
   def caveats; <<-EOS.undent
+    Consider using RVM or Cider to manage Ruby environments:
+      * RVM: http://rvm.beginrescueend.com/
+      * Cider: http://www.atmos.org/cider/intro.html
+
     By default we don't compile REE as a shared library. From their documentation:
         Please note that enabling --enable-shared will make the Ruby interpreter
         about 20% slower.

Formula/ruby.rb

@@ -36,10 +36,14 @@ class Ruby <Formula
     system "make install-doc" if ARGV.include? "--with-doc"
   end
 
-  def caveats; <<-EOS
-If you install gems with the RubyGems installed with this formula they will
-be installed to this formula's prefix. This needs to be fixed, as for example,
-upgrading Ruby will lose all your gems.
+  def caveats; <<-EOS.undent
+    Consider using RVM or Cider to manage Ruby environments:
+      * RVM: http://rvm.beginrescueend.com/
+      * Cider: http://www.atmos.org/cider/intro.html
+
+    If you install gems with the RubyGems installed with this formula they will
+    be installed to this formula's prefix. This needs to be fixed, as for example,
+    upgrading Ruby will lose all your gems.
     EOS
   end