Fix datafile issues

[werpuc]

Our users reported issues when uploading their files. This should be investigated and fixed.

• file from Kasia
• file from Magda

[werpuc]

The issue with Kasia's file: there were no values for some peptides in the second state. Since we assigned the ID when calculating deuterium uptake, there was no match to calculate differential deuterium uptake, because of different ID values. To solve this, I deleted the ID from the deuterium uptake calculations and left it in datasets and differential calculations, where is it needed.

[werpuc]

Magda's file has data for multiple proteins, and we did not test this scenario enough. Fixed.

[michbur]

These cases should be covered by tests.

[werpuc]

There is a new issue for UI tests ( #74 ). The scenarios from this task are included in the main task, so this one is closed.