Firehose endpoint in traffic controller.

[#74967290]

Signed-off-by: Joseph Rodriguez <jrodriguez@pivotal.io>

Getting a green build to start refactoring

Signed-off-by: Mike Gehard <mgehard@pivotal.io>

added doppler_endpoint package

Signed-off-by: Mike Gehard <mgehard@pivotal.io>

removed the handler argument from the DopplerEndpoint constructor

Signed-off-by: Mike Gehard <mgehard@pivotal.io>

Fix some firehose typos.

[#74967290]

Signed-off-by: Joseph Rodriguez <jrodriguez@pivotal.io>