All changes required to transfer visual fields; authentication from API controller removed temporarily (until client code is working).
Removed requirement for API to accept patient measurement for visual fields.
Patient measurements can now be created via the measurement API.
New file for importing fields as legacy events.
New base class for measurements.
Changed parent class.
Removed all references to measurement types from the API.
Merge branch 'feature/visual-fields' of github.com:openeyes/OpenEyes into feature/visual-fields

Conflicts:
	protected/models/BasePatientMeasurement.php