Add image and streaming from USB camera

Plus a little freshen up of the readme's

camera_publisher/Dockerfile

@@ -0,0 +1,22 @@
+FROM ros:kilted-ros-core
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gstreamer1.0-plugins-base \
+    gstreamer1.0-plugins-good \
+    python3-gi \
+    gir1.2-gstreamer-1.0 \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY camera_publisher.py .
+COPY entrypoint.sh .
+RUN chmod +x entrypoint.sh
+
+ENV VIDEO_DEVICE=/dev/video0
+ENV WIDTH=640
+ENV HEIGHT=480
+ENV FPS=30
+ENV CAMERA_FORMAT=raw
+ENV CAMERA_NAMESPACE=/camera
+
+ENTRYPOINT ["./entrypoint.sh"]