Specifying axis label issue #27

@astrofrog - so the line ```angles = Angle(np.asarray(values), unit=u.deg)``` was in the original ```formatter_locator.py``` file and for the x-axis ticks, the array ```values```' Quantity is ```arcsec```. By doing  ```Angle(np.asarray(values), unit=u.deg)```, we're manually changing the Quantity of ```values``` from ```arcsec``` to ```degree```. and this is why the ticks' values are different for when we do ```Angle(values) ```. I'm assuming the person who wrote this original line had a reason for doing this?