Add ability to see all upcoming events of a tag or chapter

[friedger]

handle urls /:tag -> redirect to /:tag/events /chapter/:chapterId -> redirect to /chapter/:chapterId/events

[Splaktar]

Implemented in https://github.com/gdg-x/firefly/pull/102 for the next 100 events of a tag. Still need to make a page for all events of a chapter though.

[Splaktar]

Next request will be searching for an event in the list of 100 :)