Allow StorageClass option for AwsS3 adapter

- allow setting of 'StorageClass' option in AwsS3 adapter, developer can set this to store asset as 'REDUCED_REDUNDANCY'.
- check out : http://docs.aws.amazon.com/aws-sdk-php/latest/class-Aws.S3.S3Client.html#_putObject
Allow ServerSideEncryption option for AwsS3 adapter

- allow setting of 'ServerSideEncryption' option in AwsS3 adapter, developer can set this to store asset as 'AES256' (S3 only support AES256 as of May 2014).
- check out : http://docs.aws.amazon.com/aws-sdk-php/latest/class-Aws.S3.S3Client.html#_putObject
Merge pull request #163 from leongkui/master

Allow setting 'StorageClass' and 'ServerSideEncryption' during S3 upload