Modified studentSession according to Specifikation

Student Session now has full functionality except disabling of the input
element after submitting an answer.
Also: There is a bug that leads to the timerVal not being updated
properly. This bug only occurs on source file change. (I think that's
negligible for now, but keep an eye open about that.)
See last commit message...

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Merge branch 'master' of github.com:Gozeran/GBO_Project