and add necessary values for calculating price per slice

To be sure that Cells are updated correctly when the pricing method is chosen

isn't it bad to call the parent value, as it will be called X times, X bein the number of cells

OfficeJS's user blocking third party cookie will at least stop entering their credentials many times for nothing

Followup of 340accd1

Conflicts:
	bt5/erp5_web_renderjs_ui/PathTemplateItem/web_page_module/rjs_gadget_erp5_nojqm_css.xml

In ERP5 software release we now have `mock` egg installed, so we can use it in tests instead of doing manually like this:

```python
saved_method = Class.method
def patched_method():
  ...
try:
   Class.method = patched_method
   ...
finally:
   Class.method = saved_method
```

/reviewed-on !882

Change the caching policy to one hour.

Use the CDN to publish the page if the backend is down

Cache the manifest like the HTML page but force refreshing the manifest to prevent CDN cache inconsistency.

Defining it inside portal_components ledds to business template update issue.
Bypass it by defining the expected behaviour into the web section hook.

Allow the CDN to cache the content.

Use stale_if_error to allow the CDN to return content if backend is down

Unify Vary Header.

erp5_banking_cash depends from erp5_trade via erp5_banking_core.

Gadgets:

* Support `changed` flag from `erp5.js`: 

![unsaved changes sreenshot](/uploads/cff30eae0a5d87df26bac13d43e1da3f/image.png)

* Comply with translation protocol used in ERP5JS. This does not translate, because it would not be easy ( ERP5JS translate client side with a json database of message, but in xhtml style the translation is performed server side with localizer) and not so important now. What matters is just that we can somehow reuse gadgets.

Style:

* While we are at it, fix a minor annoyance that the button in "long" dialogs where not easy to reach, at least on chrome

![before](/uploads/e03a8311571806a55fd72f6923cf855a/Screenshot_2019-05-31_at_10.38.05.png)

![after](/uploads/5753bc44fbc0f69b6adfeb14b3367236/Screenshot_2019-05-31_at_10.38.37.png)

/reviewed-on nexedi/erp5!880

Remove all globals to allow multiple live tests running on the same page.
Stop reading the test output if the browser tab doesn't have the focus.
Stop hardcoding the URL in the javascript.
Stop hardcoding other fields path in the javascript (+ embed the textarea in the gadget).

Propagate all parameters via formulator.
It will allow to use this gadget from another context document.

Run live test from the RJS UI