Add support for postgresql, oracle and microsoft sql server for amazon rds instances. This commit resolves issues #11
Use default credentials provider if there is no explicit credentials provider configured (like for the region provider). This commit resolves #13
Move the default message handler creation in the container factory.
Add a test for the auto config of the messaging.
Assert default AWSCredentialsProvider is used when no one is set.
Merge remote-tracking branch 'origin/master' into feature/boot-configuration-support

Conflicts:
	spring-cloud-aws-core/src/test/java/org/springframework/cloud/aws/core/credentials/CredentialsProviderFactoryBeanTest.java