elastic: Problems on connect

@dashaus, I copied it over from #57:

Hi, I have the same problem here:

panic: main: conn db: no Elasticsearch node available

goroutine 1 [running]:
log.Panicf(0x84de50, 0x11, 0xc2080c7e90, 0x1, 0x1)
    /usr/local/go/src/log/log.go:314 +0xd0
main.init·1()
    /Users/emilio/go/src/monoculum/init.go:40 +0x348
main.init()
    /Users/emilio/go/src/monoculum/main.go:334 +0xa4

goroutine 526 [select]:
net/http.(*persistConn).roundTrip(0xc2088ad1e0, 0xc2086a9d50, 0x0, 0x0, 0x0)
20:30:13 app         |  /usr/local/go/src/net/http/transport.go:1082 +0x7ad
net/http.(*Transport).RoundTrip(0xc20806c000, 0xc2086f6000, 0xc20873ff50, 0x0, 0x0)
20:30:13 app         |  /usr/local/go/src/net/http/transport.go:235 +0x558
20:30:13 app         | net/http.send(0xc2086f6000, 0xed4f18, 0xc20806c000, 0x21, 0x0, 
20:30:13 app         | 0x0)
    /usr/local/go/src/net/http/client.go:219
20:30:13 app         |  +0x4fc
net/http.(*Client).send(0xc08b00, 0xc2086f6000, 0x21
20:30:13 app         | , 0x0, 0x0)
    /usr/local/go/src/net/http/client.go:142 +0x15b
20:30:13 app         | net/http.(*Client).doFollowingRedirects(0xc08b00, 0xc2086f6000, 0x97cd00, 0x0, 0x0, 0x0)
20:30:13 app         |  /usr/local/go/src/net/http/client.go:367 +0xb25
net/http.(*Client).Do(0xc08b00, 0xc2086f6000, 0xc20873fce0, 0x0, 
20:30:13 app         | 0x0)
    /usr/local/go/src/net/http/client.go
20:30:13 app         | :174 +0xa4
github.com/olivere/elastic.(*Client).sniffNode(0xc208659d10, 0xc208569920, 0x15
20:30:13 app         | , 0x0, 0x0, 0x0)
20:30:13 app         |  /Users/emilio/go/src/github.com/olivere/elastic/client.go:543
20:30:13 app         |  +0x16a
20:30:13 app         | 
github.com/olivere/elastic.func·014(0xc208569920, 0x15
20:30:13 app         | )
    /Users/emilio/go/src/github.com/olivere/elastic/client.go:508 +0x47
20:30:13 app         | created by github.com/olivere/elastic.(*Client).sniff
    /Users/emilio/go/src/github.com/olivere/elastic/client.go:508 +0x744

goroutine 525 [chan receive]:
20:30:13 app         | database/sql.(*DB).connectionOpener(0xc2086de960)
    /usr/local/go/src/database/sql/sql.go:589 +0x4c
created by database/sql.Open
    /usr/local/go/src/database/sql/sql.go:452 +0x31c

goroutine 529 [IO wait]:
20:30:13 app         | net.(*pollDesc).Wait(0xc2084fe370, 0x72, 0x0
20:30:13 app         | , 
20:30:13 app         | 0x0)
    /usr/local/go/src/net/fd_poll_runtime.go:84 +0x47
net.(*pollDesc).WaitRead(0xc2084fe370, 0x0, 0x0)
    /usr/local/go/src/net/fd_poll_runtime.go:89 +0x43
net.(*netFD).Read(0xc2084fe310, 0xc208709000, 0x1000, 0x1000, 0x0, 0xed4d48, 0xc2086a9ec8)
    /usr/local/go/src/net/fd_unix.go:242 +0x40f
net.(*conn).Read(0xc20896a800, 0xc208709000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/net.go:121 +0xdc
net/http.noteEOFReader.Read(0xef0410, 0xc20896a800, 0xc2088ad238, 0xc208709000, 0x1000, 0x1000, 0xeb7010, 0x0, 0x0)
    /usr/local/go/src/net/http/transport.go:1270 +0x6e
net/http.(*noteEOFReader).Read(0xc208569b40, 0xc208709000, 0x1000, 0x1000, 0xc207f6957f, 0x0, 0x0)
    <autogenerated>:125 +0xd4
bufio.(*Reader).fill(0xc2088f3c80)
    /usr/local/go/src/bufio/bufio.go:97 +0x1ce
bufio.(*Reader).Peek(0xc2088f3c80, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /usr/local/go/src/bufio/bufio.go:132 +0xf0
net/http.(*persistConn).readLoop(0xc2088ad1e0)
    /usr/local/go/src/net/http/transport.go:842 +0xa4
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:660 +0xc9f

goroutine 530 [select]:
net/http.(*persistConn).writeLoop(0xc2088ad1e0)
    /usr/local/go/src/net/http/transport.go:945 +0x41d
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:661 +0xcbc

This occurs sometimes… not always…

curl -XGET 127.0.0.1:9200/_nodes/http?pretty=1
{
  "cluster_name" : "elasticsearch",
  "nodes" : {
    "3l_Ing0oSfWu5U63US5kxg" : {
      "name" : "Rattler",
      "transport_address" : "inet[192.168.1.91/192.168.1.91:9300]",
      "host" : "Mac-Emilio",
      "ip" : "192.168.1.91",
      "version" : "1.3.4",
      "build" : "a70f3cc",
      "http_address" : "inet[/192.168.1.91:9200]",
      "http" : {
        "bound_address" : "inet[/0:0:0:0:0:0:0:0:9200]",
        "publish_address" : "inet[/192.168.1.91:9200]",
        "max_content_length_in_bytes" : 104857600
      }
    }
  }
}