refactor(app): remove moot package.json file props

Makes the resulting package.json file cleaner, smaller and more suited
for individual apps. If a developer is publishing their generated
package to npm, one would expect them to know the correct package.json
meta properties they need.

Author: eddiemonge

templates/common/root/_package.json

@@ -1,8 +1,5 @@
 {
-  "name": "<%= _.slugify(appname) %>",
-  "version": "0.0.0",
-  "dependencies": {},
-  "repository": {},
+  "private": true,
   "devDependencies": {
     "grunt": "^0.4.5",
     "grunt-autoprefixer": "^2.0.0",