Pull out database validation into validator class

test/test_validate_config.py

@@ -46,12 +46,6 @@ class TestValidateConfig(unittest.TestCase):
     # Skip mail.
     self.validated.add('mail')
 
-  def test_validate_database(self):
-    with self.assertRaisesRegexp(Exception, 'database not properly initialized'):
-      self.validate('database', {
-        'DB_URI': 'mysql://somehost',
-      })
-
   def test_validate_jwt(self):
     with self.assertRaisesRegexp(ConfigValidationException, 'Missing JWT Verification endpoint'):
       self.validate('jwt', {