move schema.json to mediachain/translation package, include in distribution

[yusefnapora]

This does a couple things to make sure the schema.json file gets installed when installing the package via pip. We'll likely need to change this when we move the translators to the new repo, but this fixes things for now.

• moves the schema.json file to the mediachain.translation package
• updates translator.py to look in the new location
• adds include-recursive mediachain/translation *.json to MANIFEST.in so any json files in that directory tree will be included in the sdist
• adds package_data={'': ['*.json'] } to setup.py so json files inside a package actually get installed

[parkan]

Didn't have strong ideas on where to put it, fine with this