Merge branch 'fix/fd-leak' into 'master'

.gitlab-ci.yml

lib/nickserver/dispatcher.rb

lib/nickserver/reel_server.rb

lib/nickserver/request_handlers/base.rb

lib/nickserver/request_handlers/fingerprint_handler.rb

lib/nickserver/request_handlers/hkp_email_handler.rb

lib/nickserver/request_handlers/leap_email_handler.rb

lib/nickserver/request_handlers/local_email_handler.rb

lib/nickserver/source.rb

test/functional/sample_test.rb

test/remote/hkp_source_test.rb

test/remote/nicknym_source_test.rb

test/support/functional_test.rb

test/support/http_adapter_helper.rb

test/support/http_stub_helper.rb