Default RDS encryption to true

At the moment RDS encryption follows AWS defaults, ie, its set to
False. To avoid situations where data is left left secure by
mistake, we default to having encryption on, meaning that if
data security requirements are not explicitly set, we default
to the most secure.

bootstrap_cfn/config.py

@@ -470,7 +470,7 @@ def rds(self, template):
             AutoMinorVersionUpgrade=False,
             VPCSecurityGroups=[GetAtt(database_sg, "GroupId")],
             DBSubnetGroupName=Ref(rds_subnet_group),
-            StorageEncrypted=False,
+            StorageEncrypted=True,
             DependsOn=database_sg.title
         )
         resources.append(rds_instance)

tests/tests.py

@@ -281,7 +281,7 @@ def test_rds(self):
         db_instance.MasterUserPassword = 'testpassword'
         db_instance.DBName = 'test'
         db_instance.PubliclyAccessible = False
-        db_instance.StorageEncrypted = False
+        db_instance.StorageEncrypted = True
         db_instance.StorageType = 'gp2'
         db_instance.AllocatedStorage = 5
         db_instance.AllowMajorVersionUpgrade = False