Race in integration tests

[e-dard]

I hit this race on this build

==================
WARNING: DATA RACE
Read at 0x00c420a5f408 by goroutine 32:
  github.com/influxdata/influxdb/tests.(*LocalServer).WritePoints()
      /root/go/src/github.com/influxdata/influxdb/tests/server_helpers.go:414 +0x40
  github.com/influxdata/influxdb/tests.TestServer_ConcurrentPointsWriter_Subscriber.func1()
      /root/go/src/github.com/influxdata/influxdb/tests/server_test.go:7436 +0x1db

Previous write at 0x00c420a5f408 by goroutine 23:
  github.com/influxdata/influxdb/tests.(*LocalServer).Close()
      /root/go/src/github.com/influxdata/influxdb/tests/server_helpers.go:263 +0x142
  github.com/influxdata/influxdb/tests.TestServer_ConcurrentPointsWriter_Subscriber()
      /root/go/src/github.com/influxdata/influxdb/tests/server_test.go:7445 +0x13b
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:610 +0xc9

Goroutine 32 (running) created at:
  github.com/influxdata/influxdb/tests.TestServer_ConcurrentPointsWriter_Subscriber()
      /root/go/src/github.com/influxdata/influxdb/tests/server_test.go:7439 +0x11f
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:610 +0xc9

Goroutine 23 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:646 +0x52f
  testing.RunTests.func1()
      /usr/local/go/src/testing/testing.go:793 +0xb9
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:610 +0xc9
  testing.RunTests()
      /usr/local/go/src/testing/testing.go:799 +0x4ba
  testing.(*M).Run()
      /usr/local/go/src/testing/testing.go:743 +0x12f
  github.com/influxdata/influxdb/tests.TestMain()
      /root/go/src/github.com/influxdata/influxdb/tests/server_test.go:37 +0x18e
  main.main()
      github.com/influxdata/influxdb/tests/_test/_testmain.go:290 +0x1b5
==================
FAIL	github.com/influxdata/influxdb/tests	3.558s