Set span types for integrations

[delner]

This pull request ensures we're correctly tagging our spans for each service integration, for a better UI experience. After these changes are applied, the following integrations should have these service and span types:

                  Service         Span
 X ActiveRecord  - DB              SQL::TYPE
 X AWS           - WEB             WEB
 X Dalli         - CACHE           CACHE
 X ElasticSearch - DB              DB
 X Faraday       - WEB             HTTP::TYPE
 X Grape         - WEB             HTTP::TYPE
 ? HTTP          - ???             HTTP::TYPE
 X MongoDB       - DB              Mongo::TYPE
 X Rack          - WEB             HTTP::TYPE
 X Rails         - WEB, CACHE, DB  HTTP::TYPE, HTTP::TEMPLATE, SQL::TYPE, CACHE
 X Redis         - DB              Redis::TYPE
 X Resque        - WORKER          WORKER
 X Sidekiq       - WORKER          WORKER
 X Sinatra       - WEB             HTTP::TYPE, HTTP::TEMPLATE
 X SuckerPunch   - WORKER          WORKER