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

Slapos.toolbox has a new dependency to pycurl, which fails to compile if libcurl cannot be found. This commit adds the component/pycurl dependency to most of the Software Releases which have a dependency to slapos.toolbox.

I tried to do it globally, so I couldn't check the compilation of all the modified SRs. Is it a way to test that all SRs still compiled ?

Also, did I forget some important SR ?

@rafael @alain.takoudjou @kazuhiko @jm 

/reviewed-on !97

resilient: web-takeover.cgi can call a SR-specific python script to display more information on takeover web page

Also makes the interface more readable

Revert "slaprunner: fix resiliency test, add development-mode (bool) parameter for easy build webrunner in webrunner"

This reverts commit 59966611.

slaprunner: fix resiliency test, add development-mode (bool) parameter for easy build webrunner in webrunner