Updates to client docstrings

* Add a more precise description of cert_file
* change docstring placeholder to be compliant with sphinx rst
Merge remote-tracking branch 'remotes/kalikaneko/update-client-docstrings' into develop
Convert to utf8 all the strings before saving them
Merge remote-tracking branch 'chiiph-github/bug/utf8_all_the_things' into develop
Fold in changes
Merge branch 'release-0.4.1'
bump changelog to 0.4.1
Merge tag '0.4.1' into debian-0.4.1

Tag leap.soledad version 0.4.1