Update Travis Configuration (#226)

- update travis configuration
- update node-sass to 4.12 for node 12 support
- remove package-lock.json

Author: madoar

.travis.yml

@@ -12,18 +12,18 @@ branches:
   - develop
 
 node_js:
+- "12"
+- "11"
 - "10"
-- "9"
-- "8"
 
 jobs:
   include:
   - stage: Coverage
-    node_js: "10"
+    node_js: "12"
     script: npm test
     after_success:
     - npm install -g codacy-coverage
     - codacy-coverage < coverage/lcov.info
   - stage: Build
-    node_js: "10"
+    node_js: "12"
     script: npm run build