Updated setup to include how to install old version of gems, how to install redis-server in Linux, and how to install PostgreSQL in Linux

Added complete initrd and pg_ctl commands for getting started

Changed formatting of commands to prepare Postgres

Removed indents for Postgresql setup

Added blank lines between Postgres setup commands

Added \n

Added two spaces for newlines

bash to provide newlines

<pre>

Specified -R for chown command

Updated database.yml.example

Added instructions for giving username PostgreSQL privileges and password

Finished instructions for Postgres username and password

Added instructions for creating databases

Corrected typos

Added instructions for finding the path to the gems directory

Provided username and password in config/database.yml.example; updated CONTRIBUTING.md to fill in missing setup details
Merge branch 'master' of https://github.com/jhsu802701/rubygems.org

Provided username and password in config/database.yml.example; added missing setup details in CONTRIBUTING.md