contrib/docker/fedora21

dagop: unnest inner generator of revdescendants()

This just moves iterate() to module-level function.

FROM fedora:21
RUN yum install -y gcc
RUN yum install -y python-devel python-docutils
RUN yum install -y make
RUN yum install -y rpm-build
RUN yum install -y gettext
# For creating repo meta data
RUN yum install -y createrepo