add waiting since functionality
also delete the waiting_since hash if we destroy the totem
Eliminate dependency on activesupport.
Merge pull request #2 from kylev/kv_no_rails

Eliminate dependency on activesupport.
Merge branch 'add_time_waiting_held' of github.com:vijaykramesh/lita-totems into vijaykramesh-add_time_waiting_held

Conflicts:
	lib/lita/handlers/totems.rb
	lita-totems.gemspec