Prevent updating package.json if there are no actual changes

I use several additional tools with Cordova for build management. Some of those watch for changes in files in order to rebuild/redistribute. Many hard-code watching the _package.json_ file for changes. When running `cordova serve`, that calls `cordova prepare`, and _package.json_ gets updated (so does _config.xml_), whether there are actually changes to it or not (e.g., no results from a diff). This causes those build watchers to fire, rebuild, copy some files to www, which causes Cordova's auto-reload to kick in, which updates _package.json_ again, which continues this infinite cycle.

Is there a way to avoid writing the exact same content to _package.json_ that already exists in that file on every restart/reload? I get we need _config.xml_ and _package.json_ to "jive" but if there's no diff between what Cordova is about to write to _package.json_ and what's already in _package.json_, can we skip the write?

Here is [a Gist with my 2 files](https://gist.github.com/ventaur/a2b568b39a3b11bf5a7b4a75bb097605).

Start by tracing the cordova prepare path called by cordova serve and identify where package.json is written. Compare the content to the existing file before writing; done means identical content is not rewritten while actual changes still update package.json.

Written by the indexing model from the issue text.