Update gemspec summary and documentation

* Squeel supports Rails 3 & 4

squeel.gemspec

@@ -9,12 +9,12 @@ Gem::Specification.new do |s|
   s.authors     = ["Ernie Miller"]
   s.email       = ["ernie@erniemiller.org"]
   s.homepage    = "https://github.com/ernie/squeel"
-  s.summary     = %q{Active Record 3, improved.}
+  s.summary     = %q{Active Record, improved.}
   s.description = %q{
-      Squeel unlocks the power of Arel in your Rails 3 application with
+      Squeel unlocks the power of Arel in your Rails application with
       a handy block-based syntax. You can write subqueries, access named
       functions provided by your RDBMS, and more, all without writing
-      SQL strings.
+      SQL strings. Supporting Rails 3 and 4.
     }
   s.rubyforge_project = "squeel"