Add checking of appropriate project file format

[crtahlin]

If I upload the "old" format of the project file to the demo app, I get a blank screen (no contents, only background).
I presume this is a bug due to not checking/handling the format of the uploaded project file.

Expected: add some kind of error checking - if format of uploaded file not as expected, issue an error or warning and keep the contents of app same as before.

[tfius]

add check for algorithm, if not defined add default algorithm="RS256"