Update README.md

Fixed README.md for instructions on including recipe
Pass a unique digest to ruby_block within the update_file definition to prevent previous results of only_if/not_if being attributed to the current instance
added cron cookbook
[CC-675] Logrotate explicit about config permissions
Update env_vars README.md

Adds instructions for using environmental variables in a Rails console via the .bash_profile.
Update env_vars README.md

Adds instructions for using environmental variables in a Rails console via the .bash_profile and discusses alternative solutions.
Update env_vars README.md

Fixed spelling error.
Only install packages if not already installed.
Use enable_package to install memcached
Fix DJ script never killing child processes.