CS2589 - porting docusign node.js app.

- docusign_rest gem is added
- It includes docusign pages, so it does not need to redirect to node.js app for the docusign.
- DocusignController is introduced to handle requests of docusign.
- Docusign class is introduced to manage docusign interaction.
added pingdom code
added statuspage.io to the error page
replaced forums link with status
removed password for kiddiepool
added librato gem and submission of stats to librato
added rake task for sending librato stats
changes for docusign embedded signing