fix: Upgrade semantic release and grunt clean plugin

Cache npm cache and not local node modules in Travis.

Author: prantlf

.travis.yml

@@ -2,14 +2,13 @@ sudo: false
 language: node_js
 cache:
   directories:
-    - node_modules
     - ~/.npm
 notifications:
   email: false
 node_js:
-  - '4'
-  - '6'
   - '8'
+  - '6'
+  - '4'
 before_install:
   - npm install -g npm
 before_script :

package.json

@@ -29,11 +29,11 @@
     "test": "grunt",
     "coverage": "grunt instrument && GRUNT_HTML_DOM_SNAPSHOT_COVERAGE=1 grunt",
     "coveralls": "test `node --version | cut -c 2` -eq 8 && npm run coverage && grunt coveralls",
-    "semantic-release": "semantic-release pre && npm publish && semantic-release post"
+    "semantic-release": "semantic-release"
   },
   "dependencies": {
     "mkdirp": "^0.5.1",
-    "webdriverio": "^4.9.6"
+    "webdriverio": "^4.9.11"
   },
   "devDependencies": {
     "grunt": "^1.0.1",
@@ -45,7 +45,7 @@
     "grunt-istanbul": "^0.8.0",
     "grunt-selenium-standalone": "^1.0.1",
     "phantomjs-prebuilt": "^2.1.16",
-    "semantic-release": "^8.2.0"
+    "semantic-release": "^11.0.2"
   },
   "peerDependencies": {
     "grunt": ">=0.4.5"