Attempt to fix pdf generation error on heroku - update library path
Merge branch 'development'

* development:
  Invoices/emails: refactored code - pulled pdf generating code out of 'send_email' action into helper method.
  Added confirmation dialog to the 'email invoice pdf' link
  Added 'email invoice as pdf' link to invoice 'show' view.
  Invoices: updated mailer to attach a generated pdf version of the invoice. Now the user is redirected after emailing (or attempting). Updated mailer to temporarily redirect all mail to testing address.
  Updated README.
  Added import of local_env config file.
  Adding local_env config file to ignore list (to store sensitive params/vars).
  Added a route for the mailer and 'deliver' action to the invoice_controller.
  Added basic mailer for invoices. Added dev configuration for mailer.
Adding local_env.yml file import to production.
Adding rspec gem for app testing.
Merge branch 'master' into development

* master:
  Adding local_env.yml file import to production.
  Attempt to fix pdf generation error on heroku - update library path