add Blacklist and styling

@patbenatar ERMAGERD! PR REVIEW!!! :hear_no_evil: :hear_no_evil: :hear_no_evil:
@joyliu You could avoid the assignment to the local var and instead do something like:

```ruby
if Blacklist.find_by_phone_number(params["From"])
  # ... voicemail
else
  # ... forward
end
```

What do you think?