[db-api/configuration] simplify db-api and configuration so that all the connection information is in the repository url, closes #2521848 eg no more specific option of pyro ns host, group, etc. This also fixes broken ZMQ sources. Changes: * dropped pyro-ns-host, pyro-instance-id, pyro-ns-group from client side config, in favor of repository-uri. No migration done, supposing there is **no web-only config** in the wild. Also stop discovering the connection method through the repo_method class attribute of the configuration, varying according to the configuration class. This is a first step on the way to a simpler configuration handling. Notice those pyro options are still available for repository only / all-in-one configurations as they are needed to configure the pyro server. * stop telling connection method using ConnectionProperties, this is so boring. Also, drop _cnxtype from Connection and cnxtype from Session. The former is replaced by a is_repo_in_memory property and the later is totaly useless. * deprecate in_memory_cnx which becomes useless, use _repo_connect instead

from logilab.common.shellutils import generate_password
from cubicweb.server.utils import crypt_password

for user in rql('CWUser U WHERE U cw_source S, S name "system", U upassword P, U login L').entities():
    salt = user.upassword.getvalue()
    if crypt_password('', salt) == salt:
        passwd = generate_password()
        print 'setting random password for user %s' % user.login
        user.set_attributes(upassword=passwd)

commit()