Contract for sending files from frontend to backend

[MarkusHenkel]

This issue relates to: #22 #23

Issue

We need to clarify how the files sent to the frontend by the user are sent to the backend.

Frontend details

The frontend receives multiple .wig files for each condition of a job, the TSSpredator mastertable and a .gff file. Then the frontend labels each file sent with following labels: projectName, condition, strand.

How are files and labels sent to the API?

Document the solutions in the UI/UX wiki entry.