Added apps.json locally, add category results

Chief changes:

* Add apps.json as a local package resource. Had some problems with backtracking in regexes from Wappalyzer main repo, so this will let us pick a stable apps.json version to include in the package.
* Allow passing in apps.json from local path.
* Restructure package slightly.
* Add analyze_with_categories() function, which returns categories in addition to apps found.