Accessibility labels added to yml file

> Labels for accessibility added to 
first_name
last_name
email

## Narrative
In order to reduce the amount of redundant typing in the gonzo pages we need to fine tune the template files that the beaker generator creates.  

In order to produce a higher quality page we need to deliver pages that are more accessible to the visually impaired.

## Verification steps
1. Pull down the `am-accessibility-labels-on-yml-file` branch in Beaker.
1. Point your local gonzo app to local beaker on that branch i.e `gem 'beaker', :path => "../beaker"`
1. In your terminal create a test project  `rails g beaker:marketing test` 
1. Ensure that beaker generated the yml file with the 3 labels added to those form fields