Update gemspec to require origin gem >= 2.2

Author: estolfo

mongoid.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
   s.add_dependency("activemodel", ["~> 4.0"])
   s.add_dependency("tzinfo", [">= 0.3.37"])
   s.add_dependency("mongo", ["~> 2.1"])
-  s.add_dependency("origin", ["~> 2.1"])
+  s.add_dependency("origin", ["~> 2.2"])
 
   s.files        = Dir.glob("lib/**/*") + %w(CHANGELOG.md LICENSE README.md Rakefile)
   s.test_files   = Dir.glob("spec/**/*")