Backend and catapult crash on user input

[anne17]

Describe the bug
The backend or catapult dies on some types of user input. This needs to be investigated. Freeling and file input are known to be instable but should not lead to Sparv crashing.

Info for reproducing the bug

1. Sparv version used: v2 (and probably v3)

[anne17]

The FreeLing error should be fixed now, but there is still some time-out going on when the pipeline is being slow. This is why emails don't get send sometimes. There might even be different time-outs occuring, one caused by Gunicorn and one caused by the Sparv frontend.

[anne17]

Some observations are documented in this sprint report.