Skip profiling test for server versions <= 2.2

Author: estolfo

test/functional/db_test.rb

@@ -319,6 +319,7 @@ def test_db_stats
     end
 
     should "return profiling info" do
+      return unless @@version >= "2.2"
       @db.profiling_level = :all
       @coll.find()
       @db.profiling_level = :off