Fixed a couple of errors in the methods definition
Added my own IDE filed in the .gitignore file
Added a destroy method on the Gridster class
Bound leftover callbacks are one of the main causes of memory leaks, let's remove them inside the destroy method
Built new version
Fixed a minor issue when trying to destroy a non existing drag_api
Merge pull request #125 from brokenseal/master

Possible solution to memory leak #124