title: Empty graph if I try to plot plotly in IPython
body: <p>I am trying to plot using plotly offline. It works great, no errors, but I am unable to see any graph. It loads an empty graph! It is working for me in one instance of Jupyter notebook but not in another!</p>
  
  <p>Code:</p>
  
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  import numpy as np
  import re
  import requests
  import logging
  import os
  import json
  import sys
  import bokeh 
  from ipywidgets import interact
  from bokeh.io import push_notebook,show,output_notebook
  from bokeh.plotting import figure
  import cufflinks as cf
  cf.set_config_file(world_readable=True,offline=False)
  %matplotlib inline
  import seaborn as sns
  from plotly.offline import download_plotlyjs,init_notebook_mode,plot,iplot
  init_notebook_mode(connected=True)
  cf.go_offline()
  from plotly.graph_objs import *
  
  import plotly.plotly as py
  import plotly.graph_objs as go
  trace1 = go.Scatter(
      x=[0, 1, 2, 3, 4, 5],
      y=[1.5, 1, 1.3, 0.7, 0.8, 0.9]
  )
  trace2 = go.Scatter(
      x=[0, 1, 2, 3, 4, 5],
      y=[1, 0.5, 0.7, -1.2, 0.3, 0.4]
  )
  
  data = [trace1, trace2]
  iplot(data, filename='bar-line')
  </code></pre>
  
  <p>Result is an empty graph!</p>