feat(server): add net/http/pprof endpoints

Add some basic profiling endpoints over http to start digging into
memory and request latencies.
Merge pull request #479 from philips/add-debug-endpoint

add-debug-endpoint
fix(Documentation/profiling): note about using the right binary
fix(scripts/test-cluster): use v2 flags and find the path for etcd
bump(github.com/coreos/go-log): 70d039bee4b0e389e5be560491d8291708506f59
Merge pull request #486 from philips/document-profiling-binary

fix(Documentation/profiling): note about using the right binary
feat(docs): modify for sync to CoreOS website
fix(docs): remove header
Merge pull request #488 from robszumski/master

feat(docs): Prepare to sync security doc to CoreOS website
feat(metrics): Add third-party dep go-metrics

github.com/rcrowley/go-metrics commit 880a57cfbce579be3970f997eb8f589ba0b03211
feat(metrics): Add go-metrics factory code

* Add ability to push metrics to graphite
* Wrap go-metrics in a factory to return NOP timers when a graphite host
  is not provided
feat(metrics): Report timer.ae.handle metric
DO NOT MERGE - push this to goraft/raft!

* Time completion of commands by name
* Time peer heartbeats by name
feat(metrics): Publish runtime stats to graphite
refactor(metrics): replace MetricFactory with MetricsBucket

This approach removes the unnecessary logic in the calling code by
tracking all metric objects in a MetricsBucket.
refactor(metrics): document metrics pkg; unexport some things
feat(metrics): Report CommandName in leaderLoop timer
feat(metrics): Document the crap outta things
feat(metrics): configruration, debug HTTP endpoint