We have been discussing about this merge for a while.
Its main goal is to simplify things: code navigation, but also
packaging.

The rationale is that the code is more cohesive in this way, and there's
only one source package to install.

Dependencies that are only for the server or the client will not be
installed by default, and they are expected to be provided by the
environment. There are setuptools extras defined for the client and the
server.

Debianization is still expected to split the single source package into
3 binaries.

Another avantage is that the documentation can now install a single
package with a single step, and therefore include the docstrings into
the generated docs.

- Resolves: #8896

Created two methods on the backend to start and finish a batch. A dict of
callbacks is available to defer actions for the last document, allowing
temporary (changing often) metadata to be recorded only once.
Using those methods we will also be able to put all docs in one go on
the CouchDatabase implementation, but that is another step.

This was added for a Twisted 12 bug that should be gone by now.

This parameter applies the ensure_database to all existing databases,
making all of them use the latest design documents.
This can be used to migrate security documents, update handlers or any
other kind of design document.

- Resolves: #7509

netrc file was hardcoded inside create-user-db. Now it reads the path
from /etc/leap/soledad-server.conf as done on server process.
The new configuration property is called 'admin_netrc'.

README with information about latest change, missing docs and licenses,
variable naming and pep8.