Add graphicsmagick to the base images. (#109)

diff --git a/core/nodejs10Action/Dockerfile b/core/nodejs10Action/Dockerfile
index 64e6ef5..56575d5 100644
--- a/core/nodejs10Action/Dockerfile
+++ b/core/nodejs10Action/Dockerfile
@@ -18,6 +18,7 @@
 FROM node:10.15.0-stretch
 RUN apt-get update && apt-get install -y \
     imagemagick \
+    graphicsmagick \
     unzip \
     && rm -rf /var/lib/apt/lists/*
 WORKDIR /nodejsAction
diff --git a/core/nodejs8Action/Dockerfile b/core/nodejs8Action/Dockerfile
index 08ffc1c..25123f8 100644
--- a/core/nodejs8Action/Dockerfile
+++ b/core/nodejs8Action/Dockerfile
@@ -18,6 +18,7 @@
 FROM node:8.15.0
 RUN apt-get update && apt-get install -y \
     imagemagick \
+    graphicsmagick \
     unzip \
     && rm -rf /var/lib/apt/lists/*
 WORKDIR /nodejsAction
diff --git a/core/nodejsActionBase/Dockerfile b/core/nodejsActionBase/Dockerfile
index 2c8c04d..117c168 100644
--- a/core/nodejsActionBase/Dockerfile
+++ b/core/nodejsActionBase/Dockerfile
@@ -20,7 +20,11 @@
 ENV DEBIAN_FRONTEND noninteractive
 
 # Initial update and some basics.
-RUN apt-get update && apt-get install -y imagemagick && apt-get install -y unzip
+RUN apt-get update && apt-get install -y \
+    imagemagick \
+    graphicsmagick \
+    unzip \
+    && rm -rf /var/lib/apt/lists/*
 
 ADD . /nodejsAction
 # COPY the package.json to root container, so we can install npm packages a level up from user's packages, so user's packages take precedence