Email subscription v2

This is updating the email subscription retrieve to use the version 2 URL and removing the old client methods and tests in favor of the new dynamic client method
Yep, we were able to verify that adding new QS vars to a path like this one doesn't break anything:
```ruby
path = 'http://api.careerbuilder.com/v1?version=v2'
response = HTTParty.get(path, :query => { :lol => 'lol' }, :debug_output => $stderr)
opening connection to api.careerbuilder.com...
opened
<- "GET /v1?version=v2&lol=lol HTTP/1.1\r\nConnection: close\r\nHost: api.careerbuilder.com\r\n\r\n"
```