Use settings.local.yml to enable memcache during travis runs

.travis.yml

@@ -11,9 +11,6 @@ addons:
       - libarchive-dev
 services:
   - memcached
-env:
-  global:
-    - OSM_MEMCACHE_SERVERS="127.0.0.1"
 before_script:
   - sed -e 's/ IMMUTABLE / /' -e "/^--/d" db/structure.sql > db/structure.expected
   - psql -U postgres -c "CREATE DATABASE openstreetmap"
@@ -21,7 +18,7 @@ before_script:
   - psql -U postgres -f db/functions/functions.sql openstreetmap
   - cp config/travis.database.yml config/database.yml
   - cp config/example.storage.yml config/storage.yml
-  - touch config/settings.local.yml
+  - echo -e "---\nmemcache_servers:\n  - 127.0.0.1" > config/settings.local.yml
   - bundle exec rake db:migrate
   - bundle exec rake i18n:js:export
   - bundle exec rake yarn:install