Adapts default pipeline to the changes in NAMD/pypln.backend#157
Merge pull request #96 from flavioamieiro/feature/palavras_worker

Adapts default pipeline to the changes in NAMD/pypln.backend#157
Allows the configuration of the backend storage

This introduces the same code as NAMD/pypln.backend@266544ee75 .  We should
probably think of a better way to share this code.
Merge pull request #97 from flavioamieiro/feature/store_configuration

Allows the configuration of the backend storage