Use Python3, also (for some reason) include nodejs

This fixes #193

Author: stain

Dockerfile

@@ -16,12 +16,12 @@ LABEL org.label-schema.build-date=$BUILD_DATE \
   org.label-schema.schema-version="1.0"
 
 
-RUN apk add --update graphviz ttf-freefont py2-pip gcc python2-dev libc-dev && rm -rf /var/cache/apk/*
+RUN apk add --update graphviz ttf-freefont py3-pip gcc python3-dev libc-dev nodejs && rm -rf /var/cache/apk/*
 
 
 #wheel needed by ruamel.yaml for some reason
-RUN pip install wheel
-RUN pip install cwltool html5lib ruamel.yaml==0.12.4
+RUN pip3 install wheel
+RUN pip3 install cwltool html5lib ruamel.yaml==0.12.4
 
 RUN cwltool --version