Make db-name field optional for sqlserver based RDS instances

Ideally we'd actually make the field required to be not set for these
types of DB servers but that is more work

CHANGELOG.md

@@ -1,6 +1,9 @@
 ## Version UNRELEASED
 
 * Update the AWS AMI to the latest ubuntu, which includes the new kernel.
+* Partially support sqlserver based RDS instances - which *cannot* have a
+  DBName specified, so make that field not required for sqlserver backed
+  instances.
 
 ## Version 0.5.7
 

bootstrap_cfn/config.py

@@ -372,6 +372,10 @@ def rds(self, template):
         )
         resources.append(rds_instance)
 
+        # We *cant* specify db-name for SQL Server based RDS instances. :(
+        if 'db-engine' in self.data['rds'] and self.data['rds']['db-engine'].startswith("sqlserver"):
+            required_fields.pop('db-name')
+
         # TEST FOR REQUIRED FIELDS AND EXIT IF MISSING ANY
         for yaml_key, rds_prop in required_fields.iteritems():
             if yaml_key not in self.data['rds']: