CB-7350 Make createmobilespec friendlier

Unlike the other pull requests of late, I do plan to squash these (and write a better commit message).

They're split up here for review... The best way to review them is:
```sh
git log --oneline --decorate -w -p master..FETCH_HEAD
```

apache/cordova-js#78 will help with one of the other items (cordova-js has grown some dependencies, and users aren't likely to have run npm install)
Something like this is needed:
```js
+            try {
+                require(path.join(cordova_js_git_dir, "node_modules", "grunt"));
+            } catch (e) {
+                console.error("\trun `npm install` from: "+ cordova_js_git_dir);
+            }
```