Data race in service package.

[russjones]

Found the following race in 9359f6d by running go test -race -v ./... -check.f=TestAudit.

==================
WARNING: DATA RACE
Read at 0x00c42043a73a by goroutine 43:
  github.com/gravitational/teleport/lib/service.(*TeleportProcess).initAuthService.func5()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:598 +0x5cd
  github.com/gravitational/teleport/lib/service.(*LocalService).Serve()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/supervisor.go:267 +0x48
  github.com/gravitational/teleport/lib/service.(*LocalSupervisor).serve.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/supervisor.go:148 +0x232

Previous write at 0x00c42043a73a by goroutine 36:
  github.com/gravitational/teleport/lib/service.(*TeleportProcess).initAuthService.func6()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:613 +0x68
  github.com/gravitational/teleport/lib/service.(*TeleportProcess).onExit.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:631 +0x124

Goroutine 43 (running) created at:
  github.com/gravitational/teleport/lib/service.(*LocalSupervisor).serve()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/supervisor.go:144 +0x91
  github.com/gravitational/teleport/lib/service.(*LocalSupervisor).Start()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/supervisor.go:166 +0x125
  github.com/gravitational/teleport/integration.(*TeleInstance).Start()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/helpers.go:607 +0x33b
  github.com/gravitational/teleport/integration.(*IntSuite).newTeleportWithConfig()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/integration_test.go:152 +0x43c
  github.com/gravitational/teleport/integration.(*IntSuite).TestAuditOff()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/integration_test.go:1558 +0x11c
  runtime.call32()
      /usr/local/go/src/runtime/asm_amd64.s:509 +0x3a
  reflect.Value.Call()
      /usr/local/go/src/reflect/value.go:302 +0xc0
  github.com/gravitational/teleport/vendor/gopkg.in/check%2ev1.(*suiteRunner).forkTest.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/vendor/gopkg.in/check.v1/check.go:763 +0x9b0
  github.com/gravitational/teleport/vendor/gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/vendor/gopkg.in/check.v1/check.go:657 +0x89

Goroutine 36 (finished) created at:
  github.com/gravitational/teleport/lib/service.(*TeleportProcess).onExit()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:626 +0x56
  github.com/gravitational/teleport/lib/service.(*TeleportProcess).initAuthService()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:612 +0x1bf7
  github.com/gravitational/teleport/lib/service.NewTeleport()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/lib/service/service.go:327 +0x779
  github.com/gravitational/teleport/integration.(*TeleInstance).CreateEx()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/helpers.go:373 +0x18d1
  github.com/gravitational/teleport/integration.(*IntSuite).newTeleportWithConfig()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/integration_test.go:149 +0x374
  github.com/gravitational/teleport/integration.(*IntSuite).TestAuditOff()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/integration/integration_test.go:1558 +0x11c
  runtime.call32()
      /usr/local/go/src/runtime/asm_amd64.s:509 +0x3a
  reflect.Value.Call()
      /usr/local/go/src/reflect/value.go:302 +0xc0
  github.com/gravitational/teleport/vendor/gopkg.in/check%2ev1.(*suiteRunner).forkTest.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/vendor/gopkg.in/check.v1/check.go:763 +0x9b0
  github.com/gravitational/teleport/vendor/gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
      /Users/rjones/Development/go/src/github.com/gravitational/teleport/vendor/gopkg.in/check.v1/check.go:657 +0x89
==================