Update Renovate Configuration

Updates the base configuration to include:
- node support policy
- lockfile maintenance
- optimistic automerging

renovate.json

@@ -1,8 +1,14 @@
 {
   "extends": [
     "config:base",
-    "schedule:earlyMondays"
+    ":maintainLockFilesWeekly",
+    "schedule:earlyMondays",
+    ":automergeMinor"
   ],
+  "travis": { "enabled": true },
+  "node": {
+    "supportPolicy": ["lts_latest"]
+  },
   "packageRules": [
     {
       "packagePatterns": ["^postcss", "css", "autoprefixer"],