Revert "Remove coveralls reporting" (#2650)

This reverts commit 7acd497.

ci.sh

@@ -35,6 +35,10 @@ for DUMP in $(find ./ -maxdepth 1 -name 'core*' -print); do
     rm -rf ${DUMP}
 done
 
+# send coverage report to coveralls
+nyc report --reporter=lcov
+node ./node_modules/coveralls/bin/coveralls.js < ./coverage/lcov.info
+
 # return original error code
 if [[ ${EXIT_CODE} != 0 ]]; then
     exit $EXIT_CODE