Predictions are stale too quickly

[mathcolo]

Predictions are currently pulled every 60 seconds, as are trip positions. Unfortunately, if a client refreshes predictions the second before a pull, then the data age at client refresh is almost a full 120sec.

The fix, I think, is including the pull date in the nextservice response payload. Then we can calculate the data age in client side and subtract that from the prediction. We do that every second and update the value...and boom we have simulated real-time a la Track the T.

thoughts?

/cc issue #65

[tinzerillo]

I think this is a good idea! Thinking about the best way to implement

[mathcolo]

Client side of predictions streaming done in commit c2fe057, leaving issue open as the data age piece as a part of the http request is not started

[mathcolo]

Completed across the stack as of commit 2daae05, keeping ticket open until PR complete

[mathcolo]

TODO: fix favoritescontroller