Error handling for network requests in Submission Flow (#141)

* Added the TestAlreadyPairedException to the web request builder

* Added specific exceptions to all submission web requests

* Moved setting activity of DialogHelper to show call

* Re added the requestIDS to all listeners for later use

* Added Exception live data to view model

* Added error dialogs to RegisterDeviceFragment screen

* Added null check to networkResponse in VolleyError

* Added error dialogs to SubmissionTestResultFragment screen

* Fixed wrong view model call

* Added error dialogs to SubmissionResultPositiveOtherWarningFragment

* Added missing imports

* Revert "Added specific exceptions to all submission web requests"

This reverts commit 88d9027e24dd8b8c0baae7478c15cb23af403a0f.

* Revert "Added the TestAlreadyPairedException to the web request builder"

This reverts commit a4fb8272d89dd1e508a50002827fbc0dc7d86919.

* added specific error handing to services

* Switched error handlers to retrofit

* Extracted status code numbers to constants

* Added final strings for http error handling