Symptoms:
```
extras/dialer/time-scope-probe-cgroup:31:18: arithmetic expressions must consist of names and numbers
extras/dialer/time-scope-probe-cgroup: run shfmt -i 4 -w extras/dialer/time-scope-probe-cgroup
extras/dialer/time-scope-probe-proc:28:18: arithmetic expressions must consist of names and numbers
extras/dialer/time-scope-probe-proc: run shfmt -i 4 -w extras/dialer/time-scope-probe-proc
extras/in_parallel.sh:29:16: arithmetic expressions must consist of names and numbers
extras/in_parallel.sh: run shfmt -i 4 -w extras/in_parallel.sh
```
Visible on https://circleci.com/gh/kinvolk/scope/980
* remove randomness as far as possible
* make listener to close connections
* report time in a csv-friendly format
* remove tools from README
* rename time-scope-probe -> time-scope-probe-proc
* add time-scope-probe-cgroup
`extras/dialer` contains both a dialer script and dialer.go, the go
sources for the dialer server and client, to allow users to build the
dialer container themselves. Move dialer.go to a sub directory `src`
since `make clean` (running `go clean ./...`) deletes the dialer script
otherwise.
Fixup for 4d20a91a97
Signed-off-by: Michael Schubert <michael@kinvolk.io>