Do not Map per-portal in Sweeper

With named outputs we will change partitioning scheme and run sweeper
once for all portals. Results in *portals.count* times less jobs!
Setup named outputs in CamusMorphlineAvroKeyJob

Sets up named outputs for all portals specified in
`camus.sweeper.portals`. Uses AvroKeyPortalReducer to redirect output to
relevant named portal output.
Merge pull request #15 from vinted/features/sweeper-with-named-outputs

Sweeper with named outputs