[server] implement dynamic database pooler Opening too much database connection has a cost at startup and also PostgreSQL as a maximum number of connection (100 by default). This get worse when starting multiple wsgi processes, since each process has its own database pool. Instead of opening `connections-pool-size` connections to the database at startup, just open one and open more only when needed.

include *.py
include */*.py
recursive-include cubicweb_%(cubename)s *.py
recursive-include cubicweb_%(cubename)s/data *.gif *.png *.ico *.css *.js
recursive-include cubicweb_%(cubename)s/i18n *.po
recursive-include cubicweb_%(cubename)s/wdoc *
recursive-include test/data bootstrap_cubes *.py
include *.ini
prune debian
prune cubicweb-%(cubename)s.spec