Merge pull request #6783 from kennyj/rename_testname

Rename MySQLTestPurge to MySQLPurgeTest for consistency.

activerecord/test/cases/mysql_rake_test.rb

@@ -142,7 +142,7 @@ def test_drops_database
     end
   end
 
-  class MySQLTestPurge < ActiveRecord::TestCase
+  class MySQLPurgeTest < ActiveRecord::TestCase
     def setup
       @connection    = stub(:recreate_database => true)
       @configuration = {