- Travis: Drop end-of-lifed Node 6 and 8, and add Node 12 and 14

- npm: Update lint-staged per update (advanced configs removed and git add handled automatically)
- npm: Update devDeps. (all available except eslint (since some plugins still not ready) and prettier (since style changes still under discussion))

Author: brettz9

.travis.yml

@@ -1,8 +1,8 @@
 language: node_js
 node_js:
-  - 6
-  - 8
   - 10
+  - 12
+  - 14
 cache:
   directories:
     - '$HOME/.npm'