packages.json and web-view is now correctly updated on filtered updates.

This should add the following:

 * packages.json can be updated by filtered packages, without losing existing packages.

* The web-view is now generated from the newly generated packages.json. So that it's always consistent with packages.json.

* Package filter now works even when you're not using the "require-all: true" config setting.

Hope this solves most of the issues. Would really like to see this feature make it into Satis soon :)