Hook up rulers

[Keavon]

The ruler component should be ready, it just needs to be given an origin (the (0, 0) of an infinite canvas or the top left of an artboard) and majorMarkSpacing (the distance between the tallest ruler tick marks). It may also be good to provide ranges that map the major mark spacing to different increments of canvas dimensions. For example, a 1:1 relationship between document pixels and ruler pixels between a 20 and 200 pixel range, then it can double or change by an order of magnitude (10x) or something. Basically just avoid filling it with way too many ruler marks or way too few. It's also possible to set the mediumDivisions and minorDivisions if that improves the clarity to the user, but these are currently set to 5 and 2 respectively.