Detailed explanation of worker deployment configs,

especially add illustration of worker specific database
configurations. And extend DeploymentUtils a bit to handle empty
working dir.
More verbose messages in file delivering

Simple message display, but helped me a lot in identifying problematic
machines during the experiments in the last several days when the CSE
network was unstable.
Merge pull request #593 from uwescience/slxu-simple-enhancement-deployment-usability

Slxu simple enhancement deployment usability