tests: generate both content-type header and json data in json_payload()

docs: add license (MIT)

provision: `supervisorctl update` already implies a reread

provision: don't pin certs, rely on Mercurial being configured correctly Bitbucket already has a trusted, valid certificate. If extra security is needed, it shouldn't be done in user's .hgrc anyway. And since repo is a variable now, it could be on a host that's not in [hostfingerprints].

provision: if wsgi stuff had any updates, also restart fruitbar

provision: update to more YAMLy syntax

provision: use become instead of sudo

provision: move repo url and revision to vars

crud: use dict comprehension instead of dict() with generator expression

fruitbar: remove encoding declaration (not necessary, the code is ascii)