Write fuzzing testcases for `iggy-server`

[hubcio]

The aim of this issue is to create fuzz testcases that would bombard server with random data and check behavior. Server shouldn't ever crash. Assume auth is done.

https://en.wikipedia.org/wiki/Fuzzing

[hubcio]

https://github.com/BurntSushi/quickcheck

[krishvishal]

I'd like to work on this. Please assign this to me.