title: Passing datetime-like object to seaborn.lmplot
body: <p>I am trying to do a plot of values over time using seaborn linear model plot but I get the error</p>
  
  <pre><code>TypeError: invalid type promotion
  </code></pre>
  
  <p>I have read that it is not possible to plot pandas date objects, but that seems really strange given seaborn requires you pass a pandas DataFrame to the plots. </p>
  
  <p>Below is a simple example. Does anyone know how I can get this to work? </p>
  
  <pre><code>import pandas as pd
  import seaborn as sns; sns.set(color_codes=True)
  import matplotlib.pyplot as plt
  
  date = ['1975-12-03','2008-08-20', '2011-03-16']
  value = [1,4,5]
  df = pd.DataFrame({'date':date, 'value': value})
  df['date'] = pd.to_datetime(df['date'])
  
  g = sns.lmplot(x="date", y="value", data=df, size = 4, aspect = 1.5)
  </code></pre>
  
  <p>I am trying to do a plot like this one I created in r using ggplot hence why I want to use sns.lmplot
  <a href="https://i.stack.imgur.com/VhrWz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/VhrWz.png" alt="enter image description here"></a></p>