Multipart.agios 15

for testing I've created the following:

- a [servlet 3.0 app](https://github.com/cvasilak/MultiPartDemo) that logs the multipart request.
- an [iOS app](https://github.com/cvasilak/MultiPartIOSDemo)  that uses the API to upload files to the server app. The interesting bit is [here](https://github.com/cvasilak/MultiPartIOSDemo/blob/master/MultiPartIOSDemo/Classes/Controllers/AGPViewController.m#L15)