tests: Fix setting loglevel to WARN

`tests/frontend/travis/runner.sh` transforms `settings.json.template`
and overwrites `settings.json`, so creating `settings.json` doesn't
have any effect. Change the Travis setup to mutate
`settings.json.template` instead of `settings.json`.

.travis.yml

@@ -13,6 +13,11 @@ env:
     - secure: "WMGxFkOeTTlhWB+ChMucRtIqVmMbwzYdNHuHQjKCcj8HBEPdZLfCuK/kf4rG\nVLcLQiIsyllqzNhBGVHG1nyqWr0/LTm8JRqSCDDVIhpyzp9KpCJQQJG2Uwjk\n6/HIJJh/wbxsEdLNV2crYU/EiVO3A4Bq0YTHUlbhUqG3mSCr5Ec="
     - secure: "gejXUAHYscbR6Bodw35XexpToqWkv2ifeECsbeEmjaLkYzXmUUNWJGknKSu7\nEUsSfQV8w+hxApr1Z+jNqk9aX3K1I4btL3cwk2trnNI8XRAvu1c1Iv60eerI\nkE82Rsd5lwUaMEh+/HoL8ztFCZamVndoNgX7HWp5J/NRZZMmh4g="
 
+_set_loglevel_warn: &set_loglevel_warn |
+  sed -e 's/"loglevel":[^,]*/"loglevel": "WARN"/' \
+      settings.json.template >settings.json.template.new &&
+  mv settings.json.template.new settings.json.template
+
 _install_libreoffice: &install_libreoffice >-
   sudo add-apt-repository -y ppa:libreoffice/ppa &&
   sudo apt-get update &&
@@ -39,8 +44,7 @@ jobs:
     - if: fork = false
       name: "Test the Frontend without Plugins"
       install:
-        #FIXME
-        - "sed 's/\"loglevel\": \"INFO\",/\"loglevel\": \"WARN\",/g' settings.json.template > settings.json"
+        - *set_loglevel_warn
         - "tests/frontend/travis/sauce_tunnel.sh"
         - "bin/installDeps.sh"
         - "export GIT_HASH=$(git rev-parse --verify --short HEAD)"
@@ -72,8 +76,7 @@ jobs:
     - if: fork = false
       name: "Test the Frontend Plugins only"
       install:
-        #FIXME
-        - "sed 's/\"loglevel\": \"INFO\",/\"loglevel\": \"WARN\",/g' settings.json.template > settings.json"
+        - *set_loglevel_warn
         - "tests/frontend/travis/sauce_tunnel.sh"
         - "bin/installDeps.sh"
         - "rm tests/frontend/specs/*"