Fix api engine image build failed
Fix graphviz/cgraph.h not found for api engine image.
FROM python:3.6
-RUN apt-get update && apt-get install -y gettext-base graphviz && \
+RUN apt-get update && apt-get install -y gettext-base graphviz libgraphviz-dev && \
apt-get autoclean && apt-get clean && apt-get autoremove && rm -rf /var/cache/apt/
COPY src/api-engine/requirements.txt /
RUN cd / && \
