Improve performance of views filtering

[dhandeo]

1) Load the thumbnails in the list, that way when the list shows up it is ready 2) Debounce the input, so filtering will wait until the input stabilizes for say 0.3 seconds (http://stackoverflow.com/questions/21088845/can-i-debounce-or-throttle-a-watched-input-in-angularjs-using-lodash) 3) Paginate

[brianhelba]

Will fix with Girder.