(#5) Split coverage data into separate folders and added step to merge results

Author: s1hofmann

.build/build.sh

@@ -22,4 +22,4 @@ cd $targetDir
 echo "Installing node version $nodeVersion"
 nvm install $nodeVersion
 echo "npm run coverage"
-E2E_TEST=1 npm run coverage
+E2E_TEST=1 npm run coverage -- --coverageDirectory=coverage/e2e

.build/run_linux.sh

@@ -9,5 +9,6 @@ npm run compile
 echo "init e2e test subpackage"
 npm --prefix e2e/tests ci
 echo "npm run coverage"
-npm run coverage
+npm run coverage -- --coverageDirectory=coverage/unit
 docker exec nut-ci bash -c "bash $PWD/.build/build.sh ${PWD} ${TRAVIS_NODE_VERSION}"
+npm run coverage:collect