Add input validation on the proof

[talbacha]

After entering huge value in proof field, the page kept the status "saving data ....". I am not sure if the value was rejected on the server side and didn't update the page status or if the huge value caused some crash. link: http://138.68.145.52/view/samm/team-E/table key: SM.3.A

It would be beneficial to add validation on this field and show the proper message to the user.

[DinisCruz]

Good point First step is to write a test to replicate it