Docker: added noetic image. Updated travis for focal.

docker/noetic/Dockerfile

@@ -0,0 +1,6 @@
+FROM ros:noetic-perception
+# install rtabmap packages
+RUN apt-get update && apt-get install -y \
+    ros-noetic-rtabmap \
+    ros-noetic-rtabmap-ros \
+    && rm -rf /var/lib/apt/lists/

docker/noetic/latest/Dockerfile

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+FROM introlab3it/rtabmap:20.04
+
+ARG CACHE_DATE=2016-01-01
+
+RUN source /ros_entrypoint.sh && \
+    mkdir -p catkin_ws/src && \
+    cd catkin_ws/src && \
+    catkin_init_workspace && \
+    git clone https://github.com/introlab/rtabmap_ros.git && \
+    cd .. && \
+    catkin_make -j1 -DCMAKE_INSTALL_PREFIX=/opt/ros/noetic install && \
+    cd && \
+    rm -rf catkin_ws

docker/noetic/latest/hooks/build

@@ -0,0 +1,2 @@
+#!/bin/bash 
+docker build --build-arg CACHE_DATE="$(date)" --cache-from $IMAGE_NAME -f $DOCKERFILE_PATH -t $IMAGE_NAME -t $DOCKER_REPO:noetic-latest  .