Add Funnel.Percolator

`Funnel.Percolator` use `GenServer.Behaviour` and cast to percolate
messages against ElasticSeach's percolator.

Signed-off-by: chatgris <jboyer@af83.com>
Define the FeedingRouter endpoint

Signed-off-by: chatgris <jboyer@af83.com>
Start the Funnel.Percolator server

Signed-off-by: chatgris <jboyer@af83.com>
Use Funnel.Percolator in FeedingRouter

Signed-off-by: chatgris <jboyer@af83.com>