bump dependencies and fix travis node version issue

Author: schnittstabil

.travis.yml

@@ -2,10 +2,10 @@ sudo: false
 language: node_js
 node_js:
   - 'stable'
+  - '12'
   - '11'
   - '10'
   - '9'
   - '8'
-  - '7'
 after_success:
   - './node_modules/.bin/nyc report --reporter=text-lcov | ./node_modules/.bin/coveralls'

package.json

@@ -37,6 +37,6 @@
     "xo": "^0.25.3"
   },
   "dependencies": {
-    "is-plain-obj": "^1.1"
+    "is-plain-obj": "^2.0.0"
   }
 }