Make localhost development easier for new engineers

[nya-elimu]

Implement various measures that will make it easier and faster for a new contributor to launch the webapp on her/his local machine. And make it easier to add new features and perform code refactoring.

• Skip the page for filling contributor's motivation during localhost development webapp#1401
• Enable HTTPS during localhost development webapp#1571
• Document steps for adding a database migration script (when refactoring existing ORM entity)
• Use content from production environment during localhost development webapp#1942
• Reduce the time spent on importing content from CSV files during launch.
• Remove error messages appearing during launch.