Remove view layer for BlastMailer

- Deliver messages when a Blast is saved
- Write body to Markdown immediately
- Delete view layer for BlastMailer
- Include MarkdownHelper in BlastMailer
Add BlastDeliveryWorker and async operations to Blast
Add DB tasks and junk
Add deploy tasks
Refactor CI configuration

- Disable Capybara and XVFB for now on CI
- Simplify all steps with Rake tasks
Use `rake test` for running tests on CI
Use Sauce and Ruby 2.0
Configure Travis for Sauce
Use strong_parameters
Disable internal attrs protection for Rails 3
Actually use strong_parameters on the frontend
Add more functionality to Blast model
Fix SubscribersController test(s)
Fix result of blast.deliverable?
Add Sauce for running feature specs