164 - Extract camera scanner from core library

[VincentKobz]

• Create a maven artifact scanner-camera, which contains all camera-related classes (camera SDK and camera activity)
• Refactor ScannerCompatActivity: remove all camera-related mechanisms (goToCamera, layoutIdCamera, cameraViewId, cameraScanner) and camera-specific permissions. All these mechanisms are inside a new activity .
• Create CameraCompatActivity in scanner-camera (com.enioka.scanner.sdk.camera), that contains a basic layout for the camera, as an Android activity. Contains the entire camera part previously located in ScannerCompatActivity.
• Update the ReadTheDocs documentation to match the new API.

Change inside ScannerCompatActivity:

• The ScannerCompatActivity can automatically or manually (with a toggle button) fallback to the CameraCompatActivity via an explicit Android intent if the maven artifact scanner-camera is included, otherwise there is no camera-as-scanner functionality.
• Interaction buttons for scanners will now be disable if no scanner provider is found.
• Camera toggle button only shows if the camera SDK is found.

It is now possible to use only the default camera activity layout without the scanner activity layout.

The entire camera scanner API is still accessible, via the scanner-camer artifact.

[DaSpood]

Replaced by #176