Follow the specification of shacache and shadir: PUT is used in shadir,
POST is used in shacache in order to create new content. erp5_web can be used
without any modification to serve fully restfull POST interface.

Create special action for Web Site which reacts on POST type of request and
support it by low level functionality. This action is available in web view
only and affects only Web Sites configured for shacache.

Other changes:

 * do not check uploaded content, just return calculated sha
 * break compatibility during upload (better now then later)
 * avoid hiding errors during publishing content by hiding exceptions in
   WebSite_publishDocumentByActivity
 * do randomisation in tests and make them live test safe
 * connect to running web server in tests in order to use all stacks during
   uploading and downloading content
 * cleanup erp5_web_shacache and erp5_web_shadir business templates and remove
   not needed scripts
 * during testing treat running site as blackbox and do not try to be too smart