feat(touch): Add basic touch support

Add basic touch support using touch event API. It's still quite inneffective and slow, and browser scrolling is triggered while trying to move tasks.

Drawing performance for movable plugin are improved drastically using $scope.$digest() instead of $scope.apply() when possible. See http://www.bennadel.com/blog/2595-using-scope-digest-as-a-performance-optimization-in-angularjs.htm article about this subject.

It also add missing drawtask plugin files into assets directory