Update dependencies.

Author: jonkemp

package.json

@@ -9,16 +9,16 @@
   "dependencies": {
     "gulp-util": "^3.0.0",
     "inline-css": "^2.2.1",
-    "through2": "^0.6.1"
+    "through2": "^2.0.3"
   },
   "devDependencies": {
-    "coveralls": "^2.11.6",
+    "coveralls": "^3.0.0",
     "event-stream": "^3.3.2",
     "gulp": "^3.9.0",
-    "gulp-eslint": "^2.0.0",
-    "gulp-mocha": "^2.0.0",
+    "gulp-eslint": "^4.0.0",
+    "gulp-mocha": "^4.3.1",
     "mocha": "*",
-    "nyc": "^6.1.1",
+    "nyc": "^11.3.0",
     "should": "*"
   },
   "engines": {