Run tests on all node version, but coveralls only on Node 10

Author: axic

.travis.yml

@@ -4,6 +4,7 @@ node_js:
   - '8'
   - '6'
   - '4'
+
 branches:
     # We need to whitelist the branches which we want to have "push" automation.
     # Pull request automation is not constrained to this set of branches.
@@ -13,7 +14,18 @@ matrix:
   fast_finish: true
   include:
     - os: linux
+      node_js: '4'
       env: CXX=g++-4.8 TEST_SUITE=test
     - os: linux
+      node_js: '6'
+      env: CXX=g++-4.8 TEST_SUITE=test
+    - os: linux
+      node_js: '8'
+      env: CXX=g++-4.8 TEST_SUITE=test
+    - os: linux
+      node_js: '10'
+      env: CXX=g++-4.8 TEST_SUITE=test
+    - os: linux
+      node_js: '10'
       env: CXX=g++-4.8 TEST_SUITE=coveralls
 script: npm run $TEST_SUITE