getEventHandlers should convert camelcase to underscored event names
store listeners in a hash instead of a list for easy access
another test for camelcasing of handlers

remove iit
turns out Google Maps can have more than one listener on an event, so keep track of all of them instead of removing earlier listeners
modify test to ensure call
all tests passing
update docs
Merge pull request #18 from hxu/map-events

Bind event handlers for gm-map directive