* NotFound Errors are now handled by API

Can replace the following SlapTool calls:
* softwareReleaseError
* availableSoftwareRelease
* buildingSoftwareRelease
* destroyedSoftwareRelease

This new Web Service can be configured to define a list of entry points associated to JSON Form.

Those entry points are accessed by a client by doing an HTTP Post with a JSON input body.
The input JSON is validated by the JSON Form.

An output JSON body is expected as response.

It allows to reuse the erp5js header gadget.

See nexedi/erp5!2039

Stop and delete b2b services

- Support Slave Instance allocated in the same tree
- allow creating allocation consistency ticket on Instance Node
- handle allocation consistency for Slave Instance without Instance Node

This is a fixup of d42de18b.

history and statistics files are sometimes corrupted because of invalid json

We do 2 things to improve this:
 1. we use json.load to read the previous file (this will detect if the file is corrupted)
 2. we use json.dump to write the entire file at once in a temporary file and then we move this file to be atomic.

Probably this will consume more resources.

See merge request !728

  This prevents installation update modification date due Web Page
  modification date is newer.

  This fixes the coding style tests broken by:

    slapos_web_deploy: Added missing standalone-test
    slapos_web_deploy: Add rplc_coupler deploy script

  It was create a while ago, but never pushed.