title: Plotly hoverinfo shows all data points instead of current point
body: <p>I am having trouble getting plotly's <code>hoverinfo</code> attribute to display a single value for a given point. For reference I am plotting a bunch of points on a map and would like to be able to hover over a point and see its unique identifier. If I don't set any value for <code>hoverinfo</code> or <code>text</code> I see the lat and lon values for an individual point when hovering. However when I set <code>text=nodes.Node</code> and <code>hoverinfo="text"</code> I see the list of all nodes when hovering over any point. Code below produces a minimal example (in jupyter notebook):</p>
  
  <pre><code>import pandas as pd
  import plotly.offline as py
  from plotly.graph_objs import *
  py.init_notebook_mode()
  
  nodes = pd.DataFrame({
      'Node': [103,131,136,143,153],
      'Lat': [39.97703048,39.98315706,40.02686848,40.02110808,40.01174032],
      'Lon': [-83.00179533,-82.97803884,-82.97319305,-83.01509991,-82.97285888]
  })
  mapbox_access_token = some_mapbox_token
  data = Data([
      Scattermapbox(
          lat=nodes.Lat,
          lon=nodes.Lon,
          mode='markers',
          marker=Marker(
              size=2,
              color='red',
              opacity=0.7
          ),
          text=nodes.Node,
          hoverinfo='text'
      )]
  )
  layout = Layout(
      title='Nodes interacting with busiest TAZ',
      autosize=True,
      hovermode='Closest',
      showlegend=False,
      mapbox=dict(
          accesstoken=mapbox_access_token,
          bearing=0,
          center=dict(
              lat=39.983333,
              lon=-82.983333
          ),
          pitch=0,
          zoom=7.5
      ),
  )
  </code></pre>
  
  <p>Am I setting <code>text</code> incorrectly? Or is it something to do with <code>hoverinfo</code> or <code>hovermode</code>?</p>