Don't include both name & id as params

The Echonest API only supports name or id for artist profile requests.
Update this request to match the behavior of other artist requests (id
takes priority)
Support duplicate query params (e.g. bucket)

Let HTTParty generate the query URL instead of building the query string
manually. Specify the non-rails query string normalizer to prevent '[]'
from being added to the param names when generating the final URL.
Merge pull request #1 from ndelage/support-multiple-params

Support multiple params