HttpRequestWsgroups: turn bad json into log error message + return null value

(is that a good idea??)
do not create ldap filters with huge (|(uid=x1)(uid=x2)...)

instead of doing one huge filter (&(termsOfUse=CG)(|(uid=x1)(uid=x2)(uid=x3)...)
we do smaller filters with at most X uids.
for example for X=2 it gives (&(termsOfUse=CG)(|(uid=x1)(uid=x2))) then (&(termsOfUse=CG)(|(uid=x3)(uid=x4))) ...
on tests on a production openldap:
- the sweet point is between 5 and 10
- for X too large, it can be 10 times slower
- for X=1, it can be 2 times slower
SendSmsManager: handle errors returned by getMemberIds
switch to apache licence v2.0 (esup-portail now follows jasig choice)