Allow to historically add time in the past (without screenshots)

[fulldecent]

As per usability study at https://github.com/cattr-app/backend-application/issues/33

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Ideally this should allow somebody to fill in their past whole week of work in one step.

And ideally they should not be required to specify exactly when they worked. If they will input "I worked 8 hours on Monday", the computer should be able to deal with that kind of input.