Revert "Revert "[coverage reports] change to coveralls as test""

This reverts commit ee23da6dd9.

.travis.yml

@@ -28,7 +28,8 @@ before_install:
 install:
 - echo $PATH
 - source install_retry.sh
-- pip install codecov
+#- pip install codecov
+- pip install coveralls
 - pip install pypandoc
 - pip install git+git://github.com/BRML/climin.git
 - pip install autograd
@@ -39,7 +40,8 @@ script:
   - coverage run travis_tests.py
 
 after_success:
-  - codecov
+  #- codecov
+  - coveralls
 
 before_deploy:
   - cd doc