Separate into submodules

[Castaglia]

With the addition of S3 support, the mod_aws module has grown quite large. It also makes me think that there will be cases where sites wish to use only the S3 support and not the EC2 support, or vice-versa.

For such separation of functionality (and for different release cycles, and for new service additions), I am thinking that mod_aws should be separated into e.g. mod_aws, mod_aws_ec2, mod_aws_s3, _etc.