Use codecov.io instead of coveralls.

.travis.yml

@@ -9,10 +9,10 @@ before_install:
     - pip install -r requirements.txt
     - pip install pytest
     - pip install pytest-cov
-    - pip install coveralls
+    - pip install codecov
 install:
     - pip install -e .
 script:
     - py.test -l --cov=nbdime
 after_success:
-    - coveralls
+    - codecov

README.md

@@ -1,13 +1,13 @@
 # Jupyter Notebook Diff and Merge tools
 
 [![Build Status](https://travis-ci.org/martinal/nbdime.svg?branch=master)](https://travis-ci.org/martinal/nbdime)
-[![Coverage Status](https://coveralls.io/repos/martinal/nbdime/badge.svg?branch=master&service=github)](https://coveralls.io/github/martinal/nbdime?branch=master)
 
 `nbdime` contains tools for diffing and merging of Jupyter Notebooks.
 
 NB! This project is highly experimental and rapidly changing.
 
 See the latest documentation at http://nbdime.readthedocs.org.
 
-A JPEP pull request has been made at:
-https://github.com/jupyter/enhancement-proposals/pull/8
+See also description and discussion in the [JPEP pull request](https://github.com/jupyter/enhancement-proposals/pull/8).
+
+Install the [codecov browser extension](https://github.com/codecov/browser-extension#codecov-extension) to view test coverage in the source browser on github.