erp5, mariadb: Allow users to set additional environment variables to mysqld to use third party ODBC libraries for CONNECT storage engine.

more discussion at !266

/reviewed-on !329

This should fix the error below to run zope.

Error: invalid literal for int() with base 10: '10m' (line 39, in file:///srv/slapgrid/slappart7/srv/testnode/awf/inst/test0-7/etc/zope-0.conf)

Make it possible to specify the desired threshold before a requests gets saved to a temporary file instead of being read completely into memory.

@nexedi, tests do pass (I squashed commits) so unless objections today I merge it tomorrow.

https://nexedi.erp5.net/test_result_module/20180216-696E64EA

/reviewed-on !290

Current version of wendelin.core is limited in that there's no cooperation
in memory allocation between several processes sharing the same /dev/shm.
Over time, the distribution of memory among processes becomes more and more
inequal until some of them get killed due to allocation failure.

This is a temporary solution that relies on user namespaces.

…l for activities is needed.

/reviewed-on !281

Also update README accordingly.
Its becasue now erp5-site is being created automatically using software-type
default and there is no create-erp5-site software-type anymore.

See erp5@5169f193

This reverts commit 40108537.

Using the public cloudooo for all unit tests makes things
unreliable, we have every day many tests failing due to this. It
would be required to reapply this change to :
- make ERP5 more resilient to network failures when there is
  issues connecting to cloudooo
- find some automated ways to have a cloudooo per testnode machine,
  with idea of having possibility to request "where is the
  nearest service doing that"
- possibly having a CDN of cloudooo, but this does not prevent having
  a cloudooo per testnode

Since erp5@6c6b77a0, this is now a safe
operation, in that a mistake while moving databases won't result in a loss of
the catalog if the zodb is empty.

This new implementation relies on
erp5@6bb4c56e, which means that zopes
decide on their own to create the site at startup if there's none, and the
'erp5-bootstrap' service is removed from the root partition.

/reviewed-on !217

Allows requesting a caucase partition and reusing an existing caucase instance.
For client-certificate-based authentication, client must be able to access backend
directly (frontend is not possible).

Parameters not ready for stabilisation yet

The parameters not ready for stabilisation yet
This reverts commit 1db0265c.

software/erp5 & stack/erp5: Add a new parameter wendelin-core-zblk-fmt. Use it to specify wendelin.core format(ZBlk0 or ZBlk1).

Now that it really works.

Hostname is dot-less. Domain name may contain dots.

@vpelletier says:

    I do not think this is a "slave" instance, but just a sub-instance.

    "slave instance" is a way to pass parameter to a foreign instance. For example,
    frontend is an instance, and a slave instance is the rule given by an unrelated
    partition to make that existing frontend instance direct http://foo.com to 1.2.3.4:80 .

    OTOH, "balancer" is a sub-instance of ERP5's SR base instance (which is typically the root instance also).

/noticed-by @vpelletier (on !43)

Document how to setup replication.
Add support for no-zope ERP5 instance, so it is possible to setup a
replicating, full-featured ERP5 Cluster instance tree without providing
service until it needs to take over its upstream, or to become
otherwise independent.

Because this url is use by [erp5_promise](https://lab.nexedi.com/nexedi/erp5/blob/450ae11128503934b4d81de8c7c72ba7aa7948d5/bt5/erp5_promise/SkinTemplateItem/portal_skins/erp5_promise/Alarm_checkPromiseConversionServer.py#L5) to configure cloudooo in the preference, but erp5 preference is not supposed to be `cloudooo://` but just `http://` . 

FYI, this erp5_promise is the **Check Site Consistency** part described in the "ERP5 on webrunner" installation procedure as documented in https://www.erp5.com/erp5-HowTo.Request.Erp5.Instance.On.Slap.Os.Webrunner

/cc @tc @vpelletier 

/reviewed-on !94