fix(store/store_bench): don't use rand

rand just introduces more noise to the results, don't use it.
Merge pull request #484 from bcwaldon/server-config

Refactor server init code
Merge pull request #497 from philips/store-bench-no-rand

fix(store/store_bench): don't use rand
Add snapshot documentation.
Merge pull request #501 from benbjohnson/snapshot-documentation

Add snapshot documentation
Update filesystem documenation for clarity.
Better error message when setting values on directories

Without this commit etcd returns the following error message when
setting values on directories:

    {
      "errorCode":102,
      "message":"Not a file",
      "cause":"/postgres",
      "index":2
    }

While the above error message is accurate it's not very descriptive.
This commit adds a new error code/message which better describes why the
write operation failed. etcd now returns the following:

    {
      "errorCode":109,
      "message":"Cannot set value on directory",
      "cause":"/postgres",
      "index":2
    }
Merge pull request #504 from kelseyhightower/master

Better error message when setting values on directories
Merge pull request #487 from intjonathan/patch-1

English clarity in filesystem documentation.
Revert "Better error message when setting values on directories"

This reverts commit d13dd50d5107b10eaeda734d971cd4512cb4a304.
third_party: bump coreos/raft
flushInterval hack
DO NOT MERGE raft change
finish nilFlush; fix HeartbeatEventType
feat(raft): add AppendEntriesRequestGenerateType event
healthcheck
Set Peer.ConnectionString
Start timer for AppendEntriesRequestGenerateType properly
hack(log/log): remove go-log
add req/resp counters