Measure moves

[kevinburke]

Per http://toddwschneider.com/posts/a-tale-of-twenty-two-million-citi-bikes-analyzing-the-nyc-bike-share-system/, we can measure move operations by tracking when a bike with a given ID starts a trip at a different station than the one it was parked at.

This would be useful to plot to figure out how often bikes are moved and whether this number is increasing or decreasing over time.