Replace pubsub with data-layer-sdk

[Ssimonas]

Currently in service.go message receiving and publishing uses github.com/SyntropyNet/pubsub-go/pubsub. Change this to use
https://github.com/SyntropyNet/data-layer-sdk instead.
Current issue with pubsub, which does not exist with data-layer-sdk:
#45 (comment)