Release 0.9.17

Note 0.9.16 release date

Run 'docker tag' in the tag_latest task with -f

Fix setuid bit on /usr/bin/sudo, bump version to 0.9.14.

Merge pull request phusion#54 from Yggdrasil/patch-1

Fix typo in Readme

Base on baseimage-docker 0.9.13

Note release date for 0.9.11

Fix typo

Document 0.9.9 release date

Add Ruby 2.1 instruction to the Nginx example config