Add database CRUD.

moto/backends.py

@@ -7,6 +7,7 @@ from moto.ec2 import ec2_backend
 from moto.elb import elb_backend
 from moto.emr import emr_backend
 from moto.kinesis import kinesis_backend
+from moto.rds import rds_backend
 from moto.redshift import redshift_backend
 from moto.s3 import s3_backend
 from moto.s3bucket_path import s3bucket_path_backend
@@ -25,6 +26,7 @@ BACKENDS = {
     'emr': emr_backend,
     'kinesis': kinesis_backend,
     'redshift': redshift_backend,
+    'rds': rds_backend,
     's3': s3_backend,
     's3bucket_path': s3bucket_path_backend,
     'ses': ses_backend,