Allow limiting resources in dockers

[strk]

Check if it's possible to specify resource limits on a per-docker basis, to at least run tests of resource scarcity handling.

[strk]

http://stackoverflow.com/questions/16084741/how-do-i-set-resources-allocated-to-a-container-using-docker

[knutole]

Setting limits in docker-compose: https://docs.docker.com/compose/compose-file/#ulimits

[strk]

The documentation for "ulimit" misses the memory limit (-m switch in https://docs.docker.com/engine/reference/commandline/run/)

[strk]

https://docs.docker.com/compose/compose-file/#cpu-shares-cpu-quota-cpuset-domainname-hostname-ipc-mac-address-mem-limit-memswap-limit-privileged-read-only-restart-stdin-open-tty-user-working-dir