Add ability to mock/inject the CLLocationManager
Add ability to mock/inject the CLLocationManager

Created `ELCLLocationManager` protocol to define the subset of the
`CLLocationManager` API that we use. With that in place, added an
initializer that allows you to pass the manager in (i.e. _inject_ it)
into the location manager instance.

TheHolyGrail/Camelot,Electrode-iOS/ELLocation