DOC: add pypi and conda-forge badges (#231)

Author: raybellwaves

README.rst

@@ -4,6 +4,10 @@ Sklearn-pandas
 
 .. image:: https://circleci.com/gh/scikit-learn-contrib/sklearn-pandas.svg?style=svg
     :target: https://circleci.com/gh/scikit-learn-contrib/sklearn-pandas
+.. image:: https://img.shields.io/pypi/v/sklearn-pandas.svg
+   :target: https://pypi.python.org/pypi/sklearn-pandas/
+.. image:: https://anaconda.org/conda-forge/sklearn-pandas/badges/version.svg
+   :target: https://anaconda.org/conda-forge/sklearn-pandas/
 
 This module provides a bridge between `Scikit-Learn <http://scikit-learn.org/stable>`__'s machine learning methods and `pandas <https://pandas.pydata.org>`__-style Data Frames.
 In particular, it provides a way to map ``DataFrame`` columns to transformations, which are later recombined into features.
@@ -15,6 +19,9 @@ You can install ``sklearn-pandas`` with ``pip``::
 
     # pip install sklearn-pandas
 
+or conda-forge::
+
+    # conda install -c conda-forge sklearn-pandas
 
 Tests
 -----