new buildfarm client release 4.8

There is a new release of the PostgreSQL buildfarm client available, It
can be downloaded at
<https://github.com/downloads/PGBuildFarm/client-code/build-farm-4_8.tgz>

Apart from some bug fixes, changes of note include:

* A new --only-steps command line option, requested by Stephen Frost
(although not his patch)
* A new module TestUpgrade, which is enabled by default in the new
config file, to test pg_upgrade
* Report the environment that the client operates in. This will help
in debugging problems. Only values of certain white-listed
environment keys are reported for security reasons.
* A new make_jobs config parameter to run make in parallel
* A new "check" module hook (which is used by the TestUpgrade module).

Existing users will probably want to add:

modules => ['TestUpgrade'],

to their config files, and possibly also something like

make_jobs => 4,

Enjoy.

cheers

andrew