Fix SQS API

This can be tested from the AWS web console like this:

1. create a test queue
2. give all permissions to everybody
3. send a manual message like this one:

        {"Message":"{\"ban\":{\"ip\":\"192.168.0.2\"}}"}

Then run the customs server with the queue region and URL:

    BANS_REGION="ap-southeast-2" BANS_QUEUE_URL="https://sqs.ap-southeast-2.amazonaws.com/12345678/cs-sqs-test" node bin/customs_server.js

and use the `check` API before and after sending the SQS message:

    curl -H "Content-Type: application/json" -d '{"ip":"192.168.0.2","action":"accountLogin"}' http://127.0.0.1:7000/check
Merge pull request #48 from fmarier/sqs_fix

Fix SQS API
Switch config management from rc to convict (fix #46)