Fix #2 and added event hooks
Fix #2 and added event hooks

* #2 is a scope change in meteor - for now GroundDB is mounted on
window making it a global - this will be reverted in later versions as
Meteor linker is official
* Added a simple api for event hooks
* Updated documentation

dhaneshkk/db,waartaa/Meteor-GroundDB,osxi/db,Kestanous/db,divramod/db,GroundMeteor/db,urossmolnik/db