Merge pull request #232 from ialja/master

Added link to ambassadors page to event guide
Removed start date filter
Merge pull request #235 from sparkica/fix_search

Removed start date filter - fix for #231
Added OverlappingMarkerSpiderfier to handle ... well, overlaping markers
Merge pull request #236 from goranche/master

Added OverlappingMarkerSpiderfier to handle ... well, overlaping markers