added a Dockerfile for the backfiller

backfiller/Dockerfile

@@ -0,0 +1,13 @@
+FROM alpine:3.7
+# dependencies needed for compiling c extensions
+RUN apk --update add py2-pip
+
+# Install common lib first as it changes less
+COPY common /tmp/common
+RUN pip install /tmp/common && rm -r /tmp/common
+
+# Install actual application
+COPY downloader /tmp/backfiller
+RUN pip install /tmp/backfiller && rm -r /tmp/backfiller
+
+ENTRYPOINT ["python2", "-m", "backfiller", "--base-dir", "/mnt"]