Now we have a Dispatcher and two ResponseHandlers that have the same interface.

Moving towards a Chain of Responsibility pattern.

The original idea was that we would have all the celluloid related things
injected in reel_server. However it seems unlikely that we will use a
different http system anytime soon.

Removing some layers of dependency injection to reduce complexity. We
can easily bring this back if we want.

These warnings were showing on gitlab ci.

$ bundle exec rake test
/usr/local/bin/ruby -w -Ilib:test -I/builds/leap/nickserver/vendor/ruby/2.1.0/gems/rake-11.2.2/lib /builds/leap/nickserver/vendor/ruby/2.1.0/gems/rake-11.2.2/lib/rake/rake_test_loader.rb test/**/*_test.rb
/usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.12.5/lib/bundler/rubygems_integration.rb:468: warning: method redefined; discarding old find_spec_for_exe
/usr/local/lib/ruby/site_ruby/2.1.0/rubygems.rb:261: warning: previous definition of find_spec_for_exe was here
I, [2016-08-26T15:34:46.162843 #325]  INFO -- : Celluloid 0.17.3 is running in BACKPORTED mode. [ http://git.io/vJf3J ]
/builds/leap/nickserver/test/unit/request_handler_test.rb:28: warning: mismatched indentations at 'end' with 'def' at 21
/builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_protocols not initialized
/builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_select_cb not initialized
Run options: --seed 61653

# Running:

.................../builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_protocols not initialized
/builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_select_cb not initialized
.../builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_protocols not initialized
/builds/leap/nickserver/vendor/ruby/2.1.0/gems/celluloid-io-0.17.3/lib/celluloid/io/ssl_socket.rb:22: warning: instance variable @npn_select_cb not initialized
.................

Finished in 2.029982s, 19.2120 runs/s, 10.8375 assertions/s.

- add fingerprint unit tests
- add integration test
- implement by_fingerprint

This way the interface mimics the one of Celluloid Reels request.

request.respond status, content

The request handler takes a responder (the EmServer) and an adapter as initialization arguments.

It will then respond to requests by querying the sources using the adapter and calling send_response on the responder.