Fix data race w/ stopping admin server
WARNING: DATA RACE
Write by goroutine 9:
github.com/influxdb/influxdb/admin.func·001()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin.go:45 +0x18d
Previous read by goroutine 7:
github.com/influxdb/influxdb/admin.(*Server).ListenAndServe()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin.go:50 +0x3b4
github.com/influxdb/influxdb/admin_test.func·001()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin_test.go:13 +0x4a
Goroutine 9 (running) created at:
github.com/influxdb/influxdb/admin.(*Server).ListenAndServe()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin.go:49 +0x3a4
github.com/influxdb/influxdb/admin_test.func·001()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin_test.go:13 +0x4a
Goroutine 7 (finished) created at:
github.com/influxdb/influxdb/admin_test.Test_ServesIndexByDefault()
/home/ubuntu/.go_project/src/github.com/influxdb/influxdb/admin/admin_test.go:13 +0x1af
testing.tRunner()
/usr/local/go/src/testing/testing.go:447 +0x133
2e5db51441