Websocket: fix payload zero-ing

Signed-off-by: Eduardo Silva <edsiper@gmail.com>
Core: deprecate 'recycle' routines

Due to the new implementation of 'dr list' per thread, is not longer
necessary the recycle feature recently introduced to recycle duda_request_t
memory allocations on keepalive requests.

Signed-off-by: Eduardo Silva <edsiper@gmail.com>
Core: fix order when releasing resources on service_end()

Signed-off-by: Eduardo Silva <edsiper@gmail.com>