FIX Moved the --test argument in initscript; now it will only start one earlyoom process, not two!

Oops!  When two of my processes were killed in one moment, I realised that the latest version of the initscript starts TWO `earlyoom` processes in parallel!

```
00:00:00     1 25506   0 root     /bin/bash -c /usr/local/bin/earlyoom  2> "/var/log/earlyoom.log" --test
00:00:00 25506 25510   0 root     /usr/local/bin/earlyoom
00:00:00     1 25511   0 root     /bin/bash -c /usr/local/bin/earlyoom  2> "/var/log/earlyoom.log"
00:00:00 25511 25512   0 root     /usr/local/bin/earlyoom
```

This was due to a misplaced `--test` argument, and was easily fixed.

I also fixed an omission with the "exec trick" so that the parent `bash` processes is not left running.