0.8.0

• Allow routers to be configured with a list of identifiers. If an identifier
  cannot assign a dest to a request, it falls back to the next one in the list.
  • Breaking Change: Identifier plugins must now return a
    RequestIdentification object.
• Consul improvements:
  • Improve performance by only watching services as necessary and tearing
    down watches when they are no longer needed.
  • Add consistencyMode option to io.l5d.consul namer
  • Add readConsistencyMode and writeConsistencyMode options to
    io.l5d.consul dtab storage
  • Consul Namerd/DtabStore: failFast and failureAccrual is now
    disabled by default but can be enabled with the failFast option
• Improve shutdown ordering to facilitate graceful shutdown.
  • Gracefully shutdown on SIGINT and SIGTERM.
• Require tracer configuration instead of falling back to
  defaults, reducing logging noise.
• Breaking Change: The debugTrace tracer configuration flag has been
  removed in favor of the io.l5d.tracelog telemeter.
• Add io.l5d.header identifier for naming requests based on an HTTP header
• Lowercase Host header value in io.l5d.methodAndHost identifier
• Introduce transformers for post-processing the set of addresses returned by
  an interpreter.
  • Add k8s transformers to support linkerd-to-linkerd deployments when linkerd
    is deployed as a k8s daemonset.
• Remove hop-by-hop headers for better HTTP proxy compliance