title: Pandas convert numbers with a comma instead of the point for the decimal separator from objects to numbers
body: <p>Im my dataframe I have a column with numbers a format with the comma as separator, like <code>0,5</code> and the data type inferred is object. I need to convert them to numbers, but when I try
  <code>df['ColumnName'] = pd.to_numeric(df['ColumnName'])</code> I get the following exception:</p>
  <pre><code>ValueError                                Traceback (most recent call last)
  pandas/_libs/lib.pyx in pandas._libs.lib.maybe_convert_numeric()
  
  ValueError: Unable to parse string &quot;2,55&quot;
  </code></pre>
  <p>I tried looking on google and so, but couldn't find a solution. The <code>to_numeric</code> method's signature does not allow to specify a separator.</p>
  <p>Any ideas on how could I fix the problem?</p>