INTEXT-5: Initial push for AWS core and S3 adapter (Review Only)

The PR for the initial version of S3 outbound and inbound adapters. The adapter currenttly contains Inbound Adapter and Outbound Adapter only. Gateway is not yet supported and shall be taken up as part of another JIRA.
Please review the PR and add your comments, there are some more changes which I might do, will be pushed to this branch. The documentation is not yet done and needs to be done once the code is reviewed.