Target iOS 8
Migrate from manual DataProcessor to CLVisit
Explicitly request location services
Add dummy location string
Let current code run on iOS 7
Remove unused Stop methods from header
Split out NSDate beginning/end of day helpers into category
Add step counter
Remove DataProcessor spec
Persist steps to DB
WIP: Comment out CLVisit code to enable building in XCode 5

Currently, the test suite will not run in Xcode 6. Additionally, iOS 8
APIs won't compile in Xcode 5. Let's temporarily remove the iOS 8 code
to enable successful compilation in Xcode 5, and thus let the tests run.
Add empty tests for Day presenter
Move stop/step querying functionality into the respective managers

Before, querying core data for stops was happening within the Day, and
steps was happening within a class factory method on Step. Now, the
LocationManager and StepManager are responsible for that.

This has two benefits:

* It begins to point towards an abstraction where only the Manager
  objects (and, to an extent, the model objects themselves) know about
  MagicalRecord as an implementation detail.

* It makes it possible to test Day's fetching of steps and stops by
* making the querying process something that can be faked out.
Update README with iOS 8 info