[FIX] web: force load record after reload page

When reloading a page, the _actualize_mode is called before the record is loaded and the form is displayed partially in edit mode (o2m fields with delete/add icons).
This patch forces to trigger a load_record when the datarecord has not been loaded yet in the do_show merthod (opw 607910)
Merge branch '8.0' of https://github.com/odoo/odoo into 8.0-win32