Added workflowId and activityId to the logs (still work todo)
Create new input json files
Put activity list in JSON configuration file
Each activity now polls from a distinct 'taskList' which allows ActivityPoller.php to handle only certain tasks
Tasks to handle by the ActivityPoller are specified as input parameter -c or -j option
New configuration files to pass to the ActivityPoller have been added to the config folder:
 - config/transcoderActivityPoller.json : Contains the config for the Tanscoder activity
 - config/validatorActivityPoller.json : Contains the config for the two Validation activities (ValidateInput and ValidateTranscoded)
WorkflowTracker has been cleanup
ActivityPoller has be deeply remodeled.
Update README.md
Remove ValidateTranscodedAsset activity (left the file but no effect)
Added ActivityID to all log message on the Poller
Transcoding Activity that fail don't kill the workflow anymore
create "scripts" folder containing two scripts for now:
  - getFromS3.php: get file file from S3 and copy it locally
  - putInS3.php: Upload file to S3
Update README.md
Update validateInput and transcode activities to use S3 scripts.
This allow asynchronous download and upload which allow us to send heartbeat to SWF while processing
Update README.md
Fix issues with task timeout and failure
Started code for better input validator
deleted main config file and added a smaple file instead
Update README.md
composer.phar
Updated dependencies aws/aws-sdk-php (2.5.4)