Adding ssocr to docker to support Seven Segments Display (#8028)

* Adding ssocr to docker to support Seven Segments Display

* Adding cleanup

virtualization/Docker/Dockerfile.dev

@@ -12,6 +12,7 @@ MAINTAINER Paulus Schoutsen <Paulus@PaulusSchoutsen.nl>
 #ENV INSTALL_LIBCEC no
 #ENV INSTALL_PHANTOMJS no
 #ENV INSTALL_COAP_CLIENT no
+#ENV INSTALL_SSOCR no
 
 VOLUME /config
 
@@ -48,4 +49,4 @@ RUN tox -e py36 --notest
 # Copy source
 COPY . .
 
-CMD [ "python", "-m", "homeassistant", "--config", "/config" ]
+CMD [ "python", "-m", "homeassistant", "--config", "/config" ]