Finish removing coverall

There are regular issue where it shows decrease of coverage while only
non-executable lines are added (e.g. comments), this might be dues to
out of order reception of reports from travis-ci jobs.

We did activate codecov.io, which does not appear to have this issue.

Author: Carreau

.travis.yml

@@ -38,13 +38,12 @@ before_script:
     - mongo mydb_test --eval 'db.createUser({user:"travis",pwd:"test",roles:["readWrite"]});'
 
 install:
-  - pip install -U pip setuptools wheel tox-travis coveralls mypy codecov
+  - pip install -U pip setuptools wheel tox-travis mypy codecov
 
 script:
   - tox
   - if [[ $BUILD_DOCS == 'true' ]]; then tox -e docs; fi
   - if [[ $MYPY_CHECK == 'true' ]]; then mypy zarr; fi
 
 after_success:
-  - coveralls --service=travis-pro
   - codecov

README.md

@@ -47,8 +47,8 @@
 <tr>
   <td>Coverage</td>
   <td>
-    <a href="https://coveralls.io/github/zarr-developers/zarr-python?branch=master">
-    <img src="https://coveralls.io/repos/github/zarr-developers/zarr-python/badge.svg?branch=master" alt="coverage" />
+    <a href="https://codecov.io/gh/zarr-developers/zarr-python">
+    <img src="https://codecov.io/gh/zarr-developers/zarr-python/branch/master/graph/badge.svg"/ alt="coverage">
     </a>
   </td>
 </tr>

requirements_dev_optional.txt

@@ -12,7 +12,6 @@ pymongo==3.9.0
 # optional test requirements
 tox==3.14.0
 coverage==5.0.3
-coveralls==1.11.1
 flake8==3.8.3
 pytest-cov==2.7.1
 pytest-doctestplus==0.4.0

windows_conda_dev.txt

@@ -1,5 +1,4 @@
 coverage
-coveralls
 fasteners
 flake8
 monotonic