travis: improve build process and expand build matrix

Make a build heriarchy to reduce images size.
Add Android Things builds to build matrix.
Drop gcc-4 builds, use gcc-5 and gcc-6 instead.
Add SonarQube static analysis scans.

Signed-off-by: Nicolas Oliver <dario.n.oliver@intel.com>

docker/Dockerfile.sonar

@@ -0,0 +1,41 @@
+FROM upm-base
+
+# Update apt-get
+RUN apt-get -y update && \
+  # Python Build Dependencies
+  apt-get -y --no-install-recommends install python-mraa python3-mraa \
+  python python-dev python3 python3-dev python-pip python3-pip \
+  # Java Build Dependencies
+  libmraa-java default-jre default-jdk
+
+# Set JAVA_HOME
+ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64/
+
+WORKDIR /opt
+
+# Install Python Test Dependencies
+RUN pip install chardet && pip3 install chardet
+
+# Node.js Build Dependencies
+RUN wget -q -O - https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash
+ENV NVM_DIR /root/.nvm
+ARG NODE_VERSION
+RUN . $NVM_DIR/nvm.sh && nvm install $NODE_VERSION && nvm use $NODE_VERSION && \
+    npm install -g node-gyp && node-gyp install
+ENV PATH $NVM_DIR/versions/node/$NODE_VERSION/bin:$PATH
+
+# Static Code Analysis Scanner
+ENV SONAR_DIR /opt/sonar
+ENV SONAR_VER "3.0.3.778"
+WORKDIR $SONAR_DIR
+RUN wget https://sonarsource.bintray.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-${SONAR_VER}-linux.zip && \
+    wget https://sonarqube.com/static/cpp/build-wrapper-linux-x86.zip && \
+    unzip sonar-scanner-cli-${SONAR_VER}-linux.zip && \
+    unzip build-wrapper-linux-x86.zip && \
+    rm sonar-scanner-cli-${SONAR_VER}-linux.zip build-wrapper-linux-x86.zip
+ENV PATH $SONAR_DIR/sonar-scanner-${SONAR_VER}-linux/bin:$SONAR_DIR/build-wrapper-linux-x86:$PATH
+
+# Set Workdir
+WORKDIR $UPM_SRC_DIR
+
+CMD bash