Pull postgres recipe from Sentinel project

* Original is here: https://github.com/amaabca/sentinel_web/blob/master/.plow/postgres_server.sh
Snakecase filename
Instant Client fixes

* This recipe is installs dependencies required by the
ruby-oci8 gem.
* Removed hard-coded URLs and removed piece that overwrites
/etc/hosts because it will break other recipes
Restart Postgres after changing config

* Changes won't take effect until the
server restarts
* Needed because the recipe changes the config
to allow remote connections (from other machines
on the same internal network)
Allow SSH access

* Given a list of users, allow SSH access
via public key authentication
Don't update authorized_keys for non-existant users

* Check if a user exists before we create an .ssh folder and
authorized_keys file for them
* Display a better error message if the local authorized_keys
file is the same as the one on the server
Setup SSL on Nginx

* Copy local cert/pem files to a server and set permissions
* Copy local nginx virtual hosts file a server
postgres_shared.sh isn't in repo

* Removing so this script runs
Update postgres config file

* Instead of only updating config the first time Postgres is
installed, update it anytime the config changes
Create database if doesn't exist

* This will create a db if it doesn't
exist - regardless of if the user exists
Allow custom Nginx mime-types

* Allow someone to specify their own config file
for Nginx's mime.types
* We use this to serve up additional file extensions as
a particular mime type
Force an Nginx restart

* `restart nginx` didn't seem to do a stop
and a start
Update Nginx config if it's changed

* For now just hard-coding to /opt/nginx
but this should be user defined (in case they have
a package install)
Merge pull request #33 from amaabca/recipes-from-sentinel

Recipes from sentinel