travis-ci: switch to codecov.io for coverage reports

Signed-off-by: Yung-Chin Oei <yungchin@yungchin.nl>

.coveragerc

 [run]
 source = pykafka
+branch = True
+
 omit =
     */python?.?/*
     */lib-python/?.?/*.py

.travis.yml

@@ -19,7 +19,7 @@ notifications:
 
 
 install:
-    - pip install python-coveralls kazoo tox testinstances
+    - pip install codecov kazoo tox testinstances
 
 before_script:
     - "python -m pykafka.test.kafka_instance 3 --download-dir /home/travis/kafka-bin &"
@@ -30,7 +30,7 @@ script:
 
 # Calculate coverage on success
 after_success:
-    - coveralls --config_file .coveragerc
+    - codecov
 
 branches:
   only:

README.rst

 .. image:: https://travis-ci.org/Parsely/pykafka.svg?branch=master
     :target: https://travis-ci.org/Parsely/pykafka
-.. image:: https://coveralls.io/repos/Parsely/pykafka/badge.svg?branch=master
-    :target: https://coveralls.io/r/Parsely/pykafka?branch=master
+.. image:: https://codecov.io/github/Parsely/pykafka/coverage.svg?branch=master
+    :target: https://codecov.io/github/Parsely/pykafka?branch=master
 
 PyKafka
 =======