[NodeFirefox] Use security-updates to install latest firefox stable version

Author: gortazar

NodeFirefox/Dockerfile.txt

@@ -5,7 +5,9 @@ USER root
 #=========
 # Firefox
 #=========
-RUN apt-get update -qqy \
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys AF316E81A155146718A6FBD7A6DCF7707EBC211F  \
+  && echo "deb http://ppa.launchpad.net/ubuntu-mozilla-security/ppa/ubuntu trusty main" >> /etc/apt/sources.list.d/firefox-beta.list \
+  && apt-get update -qqy \
   && apt-get -qqy --no-install-recommends install \
     firefox \
   && rm -rf /var/lib/apt/lists/*