Refreshing the page of the publication job progress re-runs a publication, without any confirmation or warning to the user

A slight change of implementation should fix both this issue and BVERSION-125:

• when a publication is launched, the form should be submitted with a POST
• then this POST should take to a script that launches the publication job, obtains its id...
• ...and then redirects back to the publication configuration page, in view mode, with a job id as a parameter (a bit like what's done for the standard XWiki refactoring actions)
• a button on this page allows to navigate back to the standard publication page when the job is done (or before?)
• in order to display the progress, we can either:
  • have the handling of the job id parameter in the publication sheet
  • have a dedicated sheet that handles this, which is not bound to the publication but that is applied on demand upon publication (by passing a sheet=[...] parameter in the URL when we want to view the progress).
    • this sheet (dedicated or publication sheet) can also be used for handling the POST and launching the job from step 2
    • also, keep in mind that the launch of the job may fail at step 2 and if this happens, the user should find themselves in a place where they have a way out that is reasonable - link, breadcrumb, etc.

Work on this may be done as well with the implementation of the preview screen (BVERSION-81), so all is more or less related here.