title: Array is not mapping
body: <p>When this code loads all I see is a blank map. The markers (child component) are not rendering. I was trying to create a filter for the buttons as well but lets ignore for now until we can get the markers to appear. Any input would be appreciated!</p>
  
  <pre><code>import React from 'react';
  import {GoogleApiWrapper, Map} from 'google-maps-react';
  import Marker from '../marker.js';
  import { Button } from 'react-bootstrap';
  
  
  
  class Layout extends React.Component {
    constructor(props){
      super(props)
        this.state = {
          setFilter: ''
        }
    }
  
    setFilter(event) {
       this.setState({ selectedFilter: event.target.name });
    }
  
    render () {
      let incidents = [{lat: 32.575258, lng: -117.061613, incident_type: 'ems', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_ems.png'},
            {lat: 32.958337, lng: -117.096112, incident_type: 'fire', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_fire.png'},
            {lat: 32.728588, lng: -117.100064, incident_type: 'hazmat', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_hazmat.png'},
            {lat: 32.556325, lng: -117.055856, incident_type: 'mva', icon:'http://s3-us-west-1.amazonaws.com/et-icons/icon_report_mva.png'},
            {lat: 32.691563, lng: -117.072024, incident_type: 'fire', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_fire.png'},
            {lat: 32.805941, lng: -117.219577, incident_type: 'ems', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_ems.png' },
            {lat: 32.717516, lng: -117.164727, incident_type: 'hazmat', icon:'https://s3-us-west-1.amazonaws.com/et-icons/icon_report_hazmat.png'},
            {lat: 32.715218, lng: -117.160156, incident_type: 'mva', icon:'http://s3-us-west-1.amazonaws.com/et-icons/icon_report_mva.png'}]
      return (
        &lt;div&gt;
          &lt;div&gt;
             &lt;Button bsStyle="primary" bsSize="sm" active&gt;EMS&lt;/Button&gt;
             &lt;Button bsStyle="danger" bsSize="sm" active&gt;FIRE&lt;/Button&gt;
             &lt;Button bsStyle="warning" bsSize="sm" active&gt;HAZMAT&lt;/Button&gt;
             &lt;Button bsStyle="info" bsSize="sm" active onClick={this.state.setFilter} name="MVA"&gt;MVA&lt;/Button&gt;
          &lt;/div&gt;
            &lt;div ref="map"&gt;
              &lt;Map google={this.props.google}
                style={{width: '100%', height: '100%', position: 'relative'}}
                className={'map'}
                zoom={10}
                initialCenter={{lat: 32.7157, lng: -117.1611}}&gt;
                {incidents.filter((i) =&gt; i.incident_type === this.state.selectedFilter).map(i =&gt; {
               &lt;Marker
                 incident_type={i.incident_type}
                 position={{lat: i.lat, lng: i.lng}}
                 icon={i.icon} /&gt;
               })}
              &lt;/Map&gt;
            &lt;/div&gt;
        &lt;/div&gt;
      )
    }
  }
  
  export default GoogleApiWrapper({
    apiKey: 'AIzaSyB0P-Ql1Gdvu0baPK4xmQMchXxQoUk4YH8'
  })(Layout);
  </code></pre>