Merge pull request db-migrate#596 from DanielRuf/ci/test-nodejs-6-8-10-11

ci: test Node.js 6, 8, 10 and 11

Author: wzrdtales

.travis.yml

@@ -1,9 +1,9 @@
 language: node_js
 
 node_js:
-  - 4
   - 6
   - 8
+  - 10
   - node
 
 notifications:
@@ -42,5 +42,7 @@ addons:
 before_install:
   - export CXX=g++-4.8; export CC=gcc-4.8;
 
+install: npm install
+
 before_script:
   - cp test/db.config.ci test/db.config.json