user_spec: Use correct model name
README.md: Use new Coveralls badge URL
.travis.yml: Make script a string

Rather than a list with one element
Move Coveralls config to spec_helper

Not quite sure why, but this causes RSpec tests to be picked up by
Coveralls.
Merge branch 'fix-coverage'

* fix-coverage:
  Move Coveralls config to spec_helper
  .travis.yml: Make script a string
  README.md: Use new Coveralls badge URL
  user_spec: Use correct model name