Add an /upload-data endpoint

The upload endpoint should list the data sets that the user has
access to, and provide a form for each one to allow the user to
upload data.
Make flash messages line up

I don't think .container-fluid should be defined in each of the views.
Add flask integration tests for upload

currently I am having a problem extracting stuff from the session during
tests so we are following redirects to test messages. This is not ideal.
Will try and fix
Working code for the tests we have of upload

We should be able to get these test working without the templates which
will come in the next commit
Template changes to render all the messages upload is now sending out