[PATCH] Add parallel testing

[Stephen Finucane]

On Sun, 2020-10-04 at 12:15 +0100, Stephen Finucane wrote:
> This saves us a good deal of time, even allowing for process startup and
> general overhead. Before:
> 
>   real    6m39.103s
>   user    1m9.561s
>   sys     0m2.705s
> 
> After:
> 
>   real    4m5.267s
>   user    1m24.527s
>   sys     0m3.828s
> 
> This requires N databases, where N is the N of processors on the host.
> We need to update the docker configuration for this.
> 
> Signed-off-by: Stephen Finucane <stephen at that.guru>

Applied.