[server] Also remove tmpdir in case of error during restore database command

[server] Rename Repository's init_cnxset_pool method bootstrap See the (removed) docstring for a rationale...

[server] Replace server config's init_cnxset_pool attribute by a "bootstrap" parameter in Repository This 'init_cnxset_pool' class attribute is actually used to control whether a Repository instance should be "bootstraped" (see Repository.init_cnxset_pool() for a definition of "bootstrap") or not. I seems clearer to me to have this controlled by a boolean "bootstrap" initialization parameter in Repository.