Progress bar update

[Apotischman]

Is your feature request related to a problem? Please describe. Issue enketo/enketo-express#554 ensured that the Upload button would always appear. We are now receiving a progress bar when the user is offline and goes back online. The user doesn't know whether the application is attempting to connect and/or upload their forms. Also, since the Upload button is always available, they may not be sure whether they should click it or allow the application to upload on its own.

Describe the solution you'd like When a user is back online, the progress bar should appear when attempting to submit the completed forms. It should disappear after all successful forms are submitted. Forms with errors will remain in the queue, and the progress bar shouldn't appear after the initial submission.

[MartijnR]

Enketo-express: http://localhost:8005/x/YYYx

reported https://github.com/enketo/enketo/issues/1003

[MartijnR]

Oops, this has indeed a silly bug that enables the upload button before all uploads are finished.

• [x] fix in enketo/enketo-express https://github.com/enketo/enketo-express/pull/433
• [x] merge into this fork after PR has been approved

[MartijnR]

ready for testing @Apotischman (in master)