Add code coverage integration

.travis.yml

@@ -8,3 +8,5 @@ env:
 script:
 - ./build.sh _travis-${TRAVIS_OS_NAME}
 - ./scripts/travis_test.sh
+after_success:
+- bash <(curl -s https://codecov.io/bash)

build.sh

@@ -51,7 +51,7 @@ elif [ "$1" = "_travis-linux" ]; then
   set -x
   $0 linux
   docker run -v `pwd`:/oonibuild -w /oonibuild -t oonibuild                    \
-    go test -v -coverprofile=ooni.cov ./...
+    go test -v -coverprofile=coverage.txt -covermode=atomic ./...
 
 elif [ "$1" = "_travis-osx" ]; then
   set -x
@@ -60,7 +60,7 @@ elif [ "$1" = "_travis-osx" ]; then
   brew upgrade
   brew install measurement-kit
   $0 macos
-  go test -v -coverprofile=ooni.cov ./...
+  go test -v -coverprofile=coverage.txt -covermode=atomic ./...
 
 elif [ "$1" = "help" ]; then
   echo "Usage: $0 linux | macos | release | windows"