chore: update to node 6

Author: filipesilva

.travis.yml

@@ -2,7 +2,7 @@ dist: trusty
 sudo: required
 language: node_js
 node_js:
-  - "5"
+  - "6"
 os:
   - linux
 env:

package.json

@@ -48,7 +48,7 @@
     "gulp-tslint": "^5.0.0",
     "gulp-util": "^3.0.6",
     "gulp-watch": "^4.3.4",
-    "harp": "^0.20.3",
+    "harp": "0.21.0-pre.0",
     "html2jade": "^0.8.4",
     "indent-string": "^2.1.0",
     "jasmine-core": "^2.3.4",