Partial work toward getting results back from Lambda

Just so there's something in master and you get familiar with the lib
instead of having 2 func wide vars executionSucceeded and executionError, you can pass an error param to _newCallback and check if it's defined something like :

```
function(err){
    if(err) _sendToSqs({success: false, data: err}, finishExecution);
}
```
and call it in the try catch block like:

```
_newCallback({stack: error.stack, message: error.message})
```