contrib/docker/fedora20

bookmarks: remove useless diff()

Previous patches removed code paths referring it.

FROM fedora:20
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