This commit reorganizes the package structure. The gvaldap.settings
modules have been merged. The gvaldap.ldaptasks module has been move up
one level to have task names without the gvaldap prefix.
isort control instructions have been added to setup.cfg.
This commit moves the version number to gvaldap's __init__.py, bumps the
copyright year and starts a new development iteration. The docs/conf.py
is synchronized with the gva project's version of that file.