Avoid various memory leaks
- Removing window resize handlers on destruction
- Stop watching from parent scope on destroy so we can hopefully let go of the grid
- Added cleanup to avoid leaking grid through additions to the options object

Conflicts:
	src/directives/ng-grid.js
Add $destroy events handlers to elements

Add a handler for Angular's $destroy event to any element where we're
binding event handlers. This should help with memory leaks.
Try to unhook event listeners and watchers on element and scope destroy events. Also remove elements from DOM that are manually added on  destroy
Fixed memory leak. Had to manually remove references to DOM elements in grid instance
Change property deletes to = null, speed-up
New build with memory leak fixes
Merging upstream changes from Rob

Merge branch '2.0.8' of https://github.com/angular-ui/ng-grid into 2.0.8

Conflicts:
	build/ng-grid.debug.js
	build/ng-grid.js
	build/ng-grid.min.js
	ng-grid-2.0.8.debug.js
	ng-grid-2.0.8.min.js