Allow user to override deploy-user's homedir.

Allow the customer to override the deploy-users home-directory via
node[:opsworks][:deploy_user][:home].

This was requested by github.com/till, that uses nginx's www-data user
as deploy-user. Due to the cookbook execution order the www-data user
is not present yet, when the app is deployed.
Fix memcached pid file path on Amazon Linux.
when updating dependencies look for updates of ruby and nodejs too and run the respective recipes.
updates of nodejs are also triggered by missing packages, not only binaries.
Installing nodejs will trigger removal of old pacakges first.
updates of ruby are also triggered by missing packages, not only binaries.
when updating dependencies run the opsworks_nodejs recipe on nodejs instances.
deploy_user home is exported on the application shell environment and added comment to make paramenter overwritting functionality explizit
set default ruby executable binary path as common attribute.
remove ruby executable path, as this is keep on the common cookbook
Capture STDERR when running npm install.
Fallback definition.

Allows to retry executing resources with modified parameters.
Use fallback rubygems archive when necessary.
Retry version control checkouts.
Bump RubyGems default to 2.1.7 to match UI.
Use monit dependencies to straighten the agent restart.
only reference existing node keys when building attributes.
Make checking if nodejs must be updated OS aware.
Make checking if ruby must be updated OS aware.
Initial commit using the tomcat cookbook from https://github.com/amazonwebservices/opsworks-example-cookbooks .