Put update_coverage commands in the script called by tox

tox.ini

@@ -128,14 +128,17 @@ whitelist_externals={[post_cmd]whitelist_externals}
 
 [testenv:coverage]
 basepython=python
-passenv=COVERAGE_TOKEN
+passenv=
+    COVERAGE_TOKEN
+    CI_BUILD_REF_NAME
+    TRAVIS_BRANCH
+    TRAVIS_PULL_REQUEST
 deps=
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/requirements-dev.txt
 skip_install=True
 commands=
     py.test --cov=cas_server --cov-report term --cov-report html
-    bash -c 'cd {toxinidir}/htmlcov/; tar czf {toxinidir}/coverage.tar.gz ./'
-    bash -c 'curl -F "secret=$COVERAGE_TOKEN" -F "tar=@{toxinidir}/coverage.tar.gz" -F "project=django-cas-server" -F "branch=$(git rev-parse --abbrev-ref HEAD)" https://badges.genua.fr/local/coverage/; rm {toxinidir}/coverage.tar.gz'
+    {toxinidir}/.update_coverage "{toxinidir}" "django-cas-server"
     {[post_cmd]commands}
 whitelist_externals={[post_cmd]whitelist_externals}