Update outdated dependencies (close snowplow#685)

Author: mhadam

package.json

@@ -2,26 +2,26 @@
   "name": "snowplow-tracker",
   "version": "2.9.3",
   "dependencies": {
+    "snowplow-tracker-core": "0.6.1",
     "browser-cookie-lite": "0.3.1",
     "jstimezonedetect": "1.0.5",
     "murmurhash": "0.0.2",
     "sha1": "git://github.com/pvorb/node-sha1.git#910081c83f3661507d9d89e66e3f38d8b59d5559",
-    "snowplow-tracker-core": "0.6.1",
     "uuid": "2.0.3"
   },
   "devDependencies": {
     "@babel/core": "^7.1.2",
     "@babel/preset-env": "^7.1.0",
     "JSON": "1.0.0",
-    "grunt": "0.4.5",
+    "grunt": "^1.0.3",
     "grunt-aws": "0.6.2",
     "grunt-babel": "^8.0.0",
-    "grunt-browserify": "^5.0.0",
-    "grunt-contrib-concat": "0.5.1",
     "lodash": "^4.17.11",
+    "grunt-browserify": "^5.3.0",
+    "grunt-contrib-concat": "^1.0.1",
     "grunt-contrib-uglify": "^4.0.0",
     "intern": "3.3.2",
-    "js-base64": "2.1.9",
+    "js-base64": "^2.4.9",
     "semver": "4.3.2"
   },
   "contributors": [