Close requests sessions after benchmarks

This might be the problem of randomly crashing, long-running benchmarks
Improve server shutdown / graceful shutdown

No more killall for hyrise. Instead of waiting for random amounts of time,
explictly wait for a binary to finish. This is important, because even
killing a Hyrise process does not mean it is gone immediately.

Furthermore, users might get hung up in their fireQuery methods. Joining them
without a timeout might make a graceful termination impossible. We added a
timeout and terminate the user processes after the timeout.
Test smaller range

The bimodal splitting seems to occur for rather large output sizes
Add line information to dataframe

The identifies the run within a user
Add hyrise with reserved probe/buildtableposlists

Make sure that resizing these lists is not the bottleneck