Fix Bug, Change movingColumn to follow cursor
Fix Bug, Change movingColumn to follow cursor

MovingColumn position stays centered on the cursor unless outside
bounaries. Bug was from cursor moving up/down across the header row that pushed
the movingColumn away from the cursor.

bartkiewicz/ui-grid,InteractiveIntelligence/ng-grid,bartkiewicz/ui-grid,bartkiewicz/ui-grid,InteractiveIntelligence/ng-grid,InteractiveIntelligence/ng-grid