fix(list_units): Show description for each unit
fix(fleetctl): Default empty description to hyphen
fix(docs): update unit files from final blog post
refactor(machine): Make caller of New run RefreshState
feat(test.sh): run with -cover; print current pkg
test(machine): add testing of Machine.HasMetadata
refactor(machine): break up machine tests
test(unit): Add testing of SystemdUnitFile
fix(test): Install go cover in travis environment
fix(fleetctl): Use description from Payload
test(event): Add tests for EventBus
fix(test.sh): Test event package
test(event): assert events are not dispatched to non-handlers
refactor(test.sh): Simplify test.sh