title: append pandas dataframe automatically cast as float but want int
body: <p>How do I get pandas to append an integer and keep the integer data type? I realize I can df.test.astype(int) to the entire column after I have put in the data but if I can do it at the time I'm appending the data it seems like that would be a better way. Here is a sample:</p>
  
  <pre><code>from bitstring import BitArray
  import pandas as pd
  df = pd.DataFrame()
  
  test = BitArray('0x01')
  test = int(test.hex)
  print(test)
  df = df.append({'test':test, 'another':5}, ignore_index=True)
  
  print(df.test)
  print(df.another)
  </code></pre>
  
  <p>Here is the output:</p>
  
  <pre><code>1
  0    1.0
  Name: test, dtype: float64
  0    5.0
  Name: another, dtype: float64
  </code></pre>
  
  <p>It is changing the integers to floats.</p>