Global import/export toolbox

[theoo]

In /settings#database provide a simple tool to extract/import all information from database.
Basically, this should be a CSV from the table - fast and reliable.
In some case, when there is relations, ensure relation still exists when importing, otherwise this may lead to inconsistency.

This should serve as backup as well, a simple button "download all my CIRCL data" with privacy information should be provided.