refactor image import and add Alpine docker image

- dynamic import of QR reader
- build docker also for arm64

conftest.py

@@ -0,0 +1,10 @@
+import pytest
+
+
+def pytest_addoption(parser):
+    parser.addoption( "--relaxed", action='store_true', help="run tests in relaxed mode")
+
+
+@pytest.fixture
+def relaxed(request):
+    return request.config.getoption("--relaxed")