Retry if git command fail (to fetch for example) and also retry if slapos report a connection error

  There is no need to be faster them 2 minutes between the queries.

  Also don't interrupt of parse command output fails

Merge erp5 resilient tests code

This code tests the former ERP5 Cluster (now already in master) into a current resilience tests.

See merge request !3

Release 0.52 and start new development cycle

See merge request !2

  Accept an url which contains external configuration
  Split one log per test type

  - Get precise state of all software instances from a Hosting Subscription
  - Get the connection parameters from  all software instances from a Hosting Subscription
  - Get the instance parameters from all software instances from a Hosting Subscription
  - Move all API to connect slapos master to HAL implementation
  - Get the state of the Software Installation
  - Try to connect to monitoring tool in case of error.
  - Use TaskDistributor to determinate the tests (instead local file)
  - Use erp5.util and few erp5testnode features to determinate test revisions.
  - Download informations from the Task distributor instead use parameters (it makes implementation more flexible).

networkbench: Include ping6 and TTFB support

  Replace urlib by pycurl to get the 'Time To First Byte' responses.
  Include ping6 support
  Verbose how much package lost the connection had in case of package lost.

See merge request !1

  Replace urlib by pycurl to get the 'Time To First Byte' responses.
  Include ping6 support
  Verbose how much package lost the connection had in case of package lost.

This reverts commit 71115f74.

Conflicts:
	slapos/resiliencytest/suites/erp5cluster.py

TODO: erp5-bootstrap executable disappears, preventing it to be run when all other processes are ready.

This reverts commit c15487ed.