Add type coercion from String to List
Merge pull request #1131 from grkvlt/fix/coercion

Add type coercion from String to List
add messaging as a test dependency to jsgui, making it easier to test blueprints in the jsgui project
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()