Adds a helper task to get OS name, version and arch via SSH
OsDetails: Incorporate review comments
OsDetails: Incoporate uname call into os-details script
Rename os-and-version.sh os-details.sh.
Merge pull request #1144 from sjcorbett/os-details

Adds a helper task to get OS name, version and architecture of an entity's location via SSH
Adds StringPredicates.isBlank
Fix MutableList.copyOf(Iterable) to accept nulls
Adds Entity.addPolicy(PolicySpec) and addEnricher(EnricherSpec)
Adds entity CHILD_ADDED/CHILD_REMOVED sensors
Adds AbstractEntityAdjunct.getRequiredConfig/emit
Deprecate old enrichers (prefer new builder)
Adds Enrichers.builder()
Refactor to use Enrichers.builder()