Update consul dependency

[eikenb]

The dependencies on internal hashicorp/consul modules need to be updated to address bugs and possible security issues. While removing them or migrating them out would be very nice (#113) that is out of scope in the short term and we need these fixes...

So far I've identified several large changes. Decided to open a ticket to track my progress. That last one (StatusHandler) looks bad.

• consul/logger moved to consul/logging with a few other small changes
• PrometheusRetentionTime moved into PrometheusOpts (with more options - in consul/lib/telemetry.go)
• consul/agent/checks/check.go changed from using an Notify interface on all the check structs to using a StatusHandler object defined in that same file.