The purpose of this is to move a lot of the log and other generated
files used by the Zulip development environment into a consistent
hierarchy.
We also need to create this in tools/build-release-tarball as well,
since that runs a development environment out of a temporary
directory.
We need to update provision.py to compile the messages files, since
they are needed for the new i18n tests. And of course we need to
include the .mo files in release tarballs; there's a bit of complexity
there around how the tarball archives are created.
Umair Khan
Taranjeet Singh
Vladislav Manchev
Anders Kaseorg
Tim Abbott