Enable SPDY support

nginx comes with SPDY basically for free
Merge pull request #90 from jk/feature/enable-spdy

Enable SPDY support
recommend usage of postgresql database
jump to "Strengthening the server security" section for users with CA certified SSL certificates, close #89
upgrade to nginx-1.6.x series from the nginx/stable ppa
minify gitlab.https.permissive nginx config
no more root access, use nsenter instead
do not assign a password for root since we do not allow root access
anymore
update to the sameersbn/ubuntu:14.04.20140628 baseimage
silence setlocale message (#93)
readme: add a note w.r.t. the --env-file docker run flag
readme: fixed typo
readme: fix emphasis marker
sshd: disable pam authentication module. ref #97
readme: added instruction to remove existing container in upgrade instructions
readme: combine the -i -t flags to -it
readme: added note on app:setup rake task, ref #98
chmod /home/git/data directory. ref #34
readme: use single quote in commands, ref #92
readme: fix markdown so that it is rendered properly on the docker index.