Helsinki: Add headers -tags to program page

Adds structure to the page.
Helsinki: Use proper capitalization in talks

Looks better this way.
Helsinki: Publish selected talks on program page

If selected has been set to true, add link to program page.
Helsinki: select first talks

Set selected to true and remove proposal status.
Helsinki: Add link to program -page from proposals

Tell visitors that some talks have already been selected.
Merge pull request #1322 from jyrkiput/first-selected-talks

First selected talks