service-process: rename processId to pid

The Process model has an ID, it would normally be called processId,
so having the OS pid also be called processId is a bit confusing.
server-process: belongs to a service-instance
service-metric: statsd-ish metrics for service
fixup! metric notes
action: remove idInjection, it is the default
service-instance: has many processes, not embeds

Use a has-many relationship, so that each ServiceProcess has a unique ID
that a ServiceMetric can be associated with.
service-metric: add worker ID

I'm becoming a fan of de-normalization...
package: models are no longer backwards compatible
Merge pull request #3 from strongloop/feature/fe-metrics

WIP: front-end metrics