Added testutil.CreateTempDir().
Can set working directory for testutil.Process.

Added support for setting the working directory of the process to
testutil.StartProcess().
Prefer plug-ins in working directory.

If a plug-in name in the configuration file could refer either to a
plug-in in the working directory or the plug-in directory, prefer the
one in the working directory.
Added additional error output to watch-files.
Added additional error output on plugin failure.
Replaced watch-files.sh with built-in plug-in.

Replaced zwobot/watch-files.sh (which requires inotify-tools to be
installed) in Zwobot's own build process with the built-in watch-files
plug-in.
Deleted zwobot/watch-files.sh.

Since the built-in watch-files plug-in is used, this script is no longer
needed.
Replaced use of mirrors for Ginkgo and Gomega.

Turns out the mirroring approach I thought of doesn't really work as
intended. Replaced all imports with the official URLs. I guess we just
have to live with potential breakage.
Fixed: watch-files ignored additional arguments.
Created plug-in to replace zwobot/test.sh.
Integrated go-test plug-in into build.
Fixed go-test plugin.

It didn't actually work, for multiple reasons.
Replaced zwobot/test.sh with go-test.
Removed zwobot/test.sh.

It has been replaced by the built-in go-test plug-in.