falcon_* modules are duplicated in codebase

[duozersk]

We should think about adding the same modules only once - and then mount the codebase into required docker containers:

• falcon_demo_content
• falcon_development
• falcon_mail
• falcon_metatag
• falcon_redirect

[spleshka]

The idea is good in general. Though I'm not sure how would you propose to keep it in production? What if we put every custom module to github standalone repo and will add them to composer? Will be easier to manage across microservices.