Finalizing iteration runner with collections

So, the data setting is done for both json and csv files. One big change that was unanticipated was with the way we doing variable processing. As we were modifying the original request object subsequent variable processing was not leading to anything. eg. once {{url}} is replaced with its correct value, the `request.url` property will not undergo subsequent changes with new Global.envJson as there are no matches of `{{}}` anymore. Due to this, data files with multiple env values where working for just the first array object and not the subsequent ones.

To guard against this, I have added a `transformed` object in each request which stores the processed url thereby leaving the original one unchanged and available for subsequent use. The changes of caused by this are quite huge so we need to test (especially headers and form data) if this is working fine. Please CR carefully and let me know how this is to be done. I would suggest to checkout the part for unirest.request as you have done that part and you that better than me.

To see it in action - run newman - `./bin/newman -c tests/data/PostmanCollection.json -d tests/data/data.csv`

PS: I have added a bug for you to solve. Do look at it.

![screen shot 2014-04-23 at 12 37 40 am](https://cloud.githubusercontent.com/assets/649249/2771082/60cc0224-ca66-11e3-9fbd-86de8e7878ce.png)