Gracefully shutting down the AmazonsS3 ExecutorService

[bluesockets]

Hello. Here is a PR that will gracefully shuts down the S3 ExecutorService. Currently the shutdown() method issues a shutdownNow() that interrupts the com.amazonaws.http.IdleConnectionReaper causing it to throw an java.lang.InterruptedException. Issuing a shutdown() with a 30 second timeout gets rid of the exception, and allows some time for the client to spin down.

Thanks for your work on aws-wrap

[alexmnyc]

@dwhjames this looks good. Can someone please merge?

[malcolmgreaves]

Is this still actively maintained? @dwhjames

[mingchuno]

@bluesockets I have fork and merged your PR. I have also publish it under version 0.9.0 https://github.com/mingchuno/aws-wrap