Fix the use of 'update_attributes'
Fix participant attribute lists for actions
Fix processing empty params
Move extracting pagination parameters to a method
Simplify simple_layout
Use `haml` instead of `render :haml`

This functionality of `haml` method is available in Sinatra 1.4.
Move lines around
Format
Show talk proposals for Scientific Committee

Provide a simple HTML page with talk proposals for the scientific committee
at /en/org/articles/talk_proposals_for_scientific_committee and an utility
tab to preview and access this page.
Add subject to emails in talk proposal list
Move GoogleMaps url creation to a helper function
Consider the COMB registration page static

The COMB registration page is a static form that redirects to the main registration form.  So it should be treated as other static pages.
Show "hotels" without specific address smarter
Make the accommodation page dynamic