add revisioning task to gulp build

* 'public' directory is now removed on gulp build
* Copies built .css and .js files to <filename>-<hash>.<extension>
* Replaces references from built .html files to match the revisioned files
* Keeps the original built files intact, but this is most likely going to change in the future

package.json

@@ -29,6 +29,8 @@
     "gulp-autoprefixer": "1.0.1",
     "gulp-duration": "0.0.0",
     "gulp-jade": "~0.9.0",
+    "gulp-replace": "^0.5.3",
+    "gulp-rev": "^4.0.0",
     "gulp-sourcemaps": "^1.3.0",
     "gulp-streamify": "0.0.5",
     "gulp-stylus": "~2.0.0",
@@ -39,6 +41,7 @@
     "karma-cli": "0.0.4",
     "karma-jasmine": "~0.2.2",
     "node-notifier": "^4.2.1",
+    "rimraf": "^2.3.4",
     "vinyl-source-stream": "~1.0.0",
     "watchify": "^3.2.1"
   },