Fix for nav helper to select active link

The nav_link_to wasn't working properly for almanac pages. This fix
checks whether or not the current resource is an almanac page and 
makes sure it's active.
Add Press page
Add Learn section to Almanac

Learn section with pages about presentations, workshops and
lightning talks. Pages still need to be written though.
Comment out almanac nav links to pages that don't exist yet
Move Q&As to Almanac and rewrite of index & schedule