Add logo and badges (#85)

README.md

@@ -1,3 +1,7 @@
+<img src="doc/source/_static/logo.png" height=100></img>
+
+[![Build Status](https://travis-ci.org/arviz-devs/arviz.svg?branch=master)](https://travis-ci.org/arviz-devs/arviz) [![Coverage Status](https://coveralls.io/repos/github/arviz-devs/arviz/badge.svg?branch=master)](https://coveralls.io/github/arviz-devs/arviz?branch=master)
+
 # ArviZ
 ArviZ (pronounced "AR-_vees_") is a Python package for exploratory analysis of Bayesian models.
 Includes functions for posterior analysis, model checking, comparison and diagnostics.
@@ -14,4 +18,4 @@ Another option is to clone the repository and install using `python setup.py ins
 
 ## Dependencies
 
-Arviz is tested on Python 3.6 and depends on NumPy, SciPy, Pandas and Matplotlib.
+Arviz is tested on Python 3.6 and depends on NumPy, SciPy, Pandas and Matplotlib.