continue development...
Mount selinuxfs read-only and on new location when possible

We need to mount the selinuxfs read-only inside the chroot to make the
userspace think that selinux is disabled. This is required, otherwise
dpkg will fail as no policy is installed in the chroot.

We are also moving the mountpoint of the selinuxfs from /selinux to
/sys/fs/selinux if the /selinux directory is not present on disk. This
directory has been removed in jessie.
Add debian/changelog entry for Laurent Bigonville's patch addressing #682068.
piuparts-report.py: create https URLs in source_summary_url().
fix spelling of "ditto". (Closes: #746724)
TODO: document some bug numbers
temp. ignore debsums results for wheezy2jessie and wheezy2bpo2jessie
piuparts.py: Add to ignored_files: + /etc/sub{g,u}id[-] introduced by shadow 1:4.2-1.
piuparts.conf.sample: explain default location of the file
Install cron files for piupartsm and piupartss users in /usr/share/doc/piuparts-(master|slave)/examples/. (Closes: #746721)
Install piuparts.conf.sample in /usr/share/doc/piuparts-master/examples/.
Install slave_run and slave_join in /usr/bin/ (Closes: #746718)
Fix log directory creation in piuparts-report. (Closes: #746722)
scripts/pre_install_database-server: work around #707075 and force MyISAM storage engine on upgrades from wheezy
fixup: scripts/pre_install_database-server: work around #707075 and force MyISAM storage engine on upgrades from wheezy
fixup: scripts/pre_install_database-server: work around 707075
fixup the easy way and workaround 707075 by just not testing with mysql
Revert "drop scripts/pre_upgrade_exceptions"

This reverts commit 51f34be8a3339465c6cf68767bc7ea07bfcf5b9d.
create graph of bugs filed and display it piuparts.d.o welcome page.
fix whitespaces