Fix commit order of CMFActivity SQL connection on nodes with several zserver threads

When a ZODB connection is closed, it usually returns to a ZODB pool and may be
reused by another thread. If the SQL connection was open and is still in ZODB
cache, the _v_database_connection attribute is still there:
ActivityConnection.connect() is not called and a new instance of ZMySQLDA.db.DB
is created for the new thread without initializing its sort key.
Use already existing system preference and created accessor rather than hard coded value which was different from
default for the system preference
This can lead to different cache ids generated for same content by different
parts of the code -> duplication of same data in cache backend.
add expected failure to be fixed after
remove unused import
Fix type CMF Activity SQL connection on ERP5 Site creation

... instead of relying on automatic migration.

This fixes TestCMFActivity.test_connection_sortkey on Zope 2.13
Do not sort by default.

This hurts performances a lot.
make erp5.util.testnode able to resist to problems with slapos proxy
release erp5.util 0.4.28
make erp5.util.testnode able to resist to problems with slapos proxy
release erp5.util 0.4.28
keep almost no tmp files, sometimes there is many Gb in /tmp after one day
release erp5.util 0.4.30
Keep warnings enabled by default on Python 2.7
initial import of distributors used for unit testing
add missing action to activity tool
correctly quote titles, before a space in title was introducing mess
use less test suite per node to keep disk space
remove useless spaces
Add 'funding' in inventory API

To migrate, run:
alter table stock add column funding_uid bigint unsigned after payment_uid, add index funding_uid (funding_uid);
alter table inventory_stock add column funding_uid bigint unsigned after payment_uid;
Add 'payment_request' in inventory API

To migrate, run:
alter table stock add column payment_request_uid bigint unsigned after funding_uid, add index payment_request_uid (payment_request_uid);
alter table inventory_stock add column payment_request_uid bigint unsigned after funding_uid;