Detailed error messages when nomad start job or delete job fails

[sohaibiftikhar]

When submitting or deleting a job to nomad fails (for example, due to a malformed input parameter like URL), the reported failure is a NomadRequestFailed exception which only tracks the request URI and the response code (see code). It might be useful to look at the result.body and use it in the NomadRequestFailed class to show meaningful errors.

As a first step, we do not need to do this in the UI but can at least have logs on the backend that makes it easier to figure out what went wrong without having to use a hit and try mechanism.