Separate app and mfr config
Put mfr static assets in their own folder that is gitignored
Allow local file-based configuration of mfr player
Make sure mfr_confi_local.py is created when player is run
Update CONTRIBUTING
Add invoke task to clear mfr assets
Merge pull request #69 from CenterForOpenScience/player

Player fixes
Remove mfr_md from core
Add README warning
Update contributing docs
Merge branch 'dev' of https://github.com/CenterForOpenScience/modular-file-renderer into dev