[server] Separate repository bootstrap from initialization
Thus we now call 'bootstrap' here and there explicitly and remove call of this
method in Repository.__init__(). This way instantiation of a Repository does
not *implicitly* triggers the "bootstrap" step, which is arguably not a
trivial thing and thus deserves to be independent.
In __init__, set 'shutting_down' attribute to None and then to False in
bootstrap as a mean to indicate that, when initialized, a repository is
neither shutting down nor started (not sure where this is used though).
version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
https://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))