Use production and development index files

[Sekhmet]

Fixes #997

Changes:

• dist/ folder has been deleted
• templates/index.html is used for development purposes
• templates/production_index.html is used for production

[bonustrack]

Isn't more common to have a dist folder instead of templates?

[Sekhmet]

For built files I think so, but they are not built yet (at least one of them). production-index.html will be built using html-webpack-plugin first, and then moved to public/ folder.