Ok, removing examples from Travis for good

Now node-sass won't compile on Node 6, probably since travis nodes say
they have no C++11x compiler and node 4+ native extensions require such
a supporting compiler.

This isn't adding much value and is too much pain to manage, I'll just
keep to running the examples locally.

.travis.yml

@@ -10,10 +10,8 @@ install: npm install --ignore-scripts
 script:
   - npm run lint
   - npm run test:coverage
-  - npm run test-examples
 after_success:
   - npm run coverage:ci
 cache:
   directories:
-  - node_modules
-  - examples/*/node_modules
+  - node_modules