title: issue in run mongostat for auth enabled mongodb
body: <p>I just implemented auth for mongodb, There is  a user ‘admin’
  in db ‘admin’ and ‘appadmin’ in db ‘mydb’ all working fine. below
  are my db auth settings:</p>
  
  <pre><code>use admin
  db.auth(‘’, ‘’)
  db.getUsers()
  [
      {
          "_id" : "admin.admin",
          "user" : "admin",
          "db" : "admin",
          "roles" : [
              {
                  "role" : "userAdminAnyDatabase",
                  "db" : "admin"
              },
              {
                  "role" : "clusterMonitor",
                  "db" : "admin"
              }
          ]
      }
  ]
  
  
  use mydb
  db.auth()
  db.getUsers()
  
      {
          "_id" : "mydb.appadmin",
          "user" : "mydb",
          "db" : "mydb",
          "roles" : [
              {
                  "role" : "readWrite",
                  "db" : "mydb"
              },
              {
                  "role" : "userAdmin",
                  "db" : "mydb"
              }
          ]
      }
  ].
  </code></pre>
  
  <p>If I run the following, </p>
  
  <pre><code>mongostat --username=admin --password=mypassword  --authenticationDatabase=admin
  insert query update delete getmore command flushes mapped  vsize   res faults qr|qw ar|aw netIn netOut conn     time
      *0    *0     *0     *0       0     1|0       0 240.0M 678.0M 91.0M      0   0|0   0|0   79b    10k    1 11:49:18
      *0    *0     *0     *0       0     1|0       0 240.0M 678.0M 91.0M      0   0|0   0|0   79b    10k    1 11:49:19
      *0    *0     *0     *0       0     1|0       0 240.0M 678.0M 91.0M      0   0|0   0|0   79b    10k    1 11:49:20
  </code></pre>
  
  <p>But when I run </p>
  
  <pre><code>* mongostat --username=appadmin --password=mypassword  --authenticationDatabase=mydb
  
          Failed: not authorized on admin to execute command { serverStatus: 1, recordStats: 0 },
  </code></pre>
  
  <p>So I tried to add role ‘clusterMonitor’ in mydb.</p>
  
  <pre><code>db.updateUser(“appadmin”, {roles: [{role: "readWrite", db: “mydb”}, {role: "userAdmin", db: “mydb”}, {role: "clusterMonitor", db: “mydb”}]})
  E QUERY    Error: Updating user failed: No role named clusterMonitor@mydb.
  </code></pre>
  
  <p>What is the best way to do mongostat in a auth enabled mongoldb? Please help me to fix the issue or suggest best auth settings.
  Note: my mongodb version 3.0.6</p>