Installer refactoring

WIP

Note to myself:
* Double "Try again? (Y)" loop
* With flag -create-mysql-user=false user is still asked if mysql user should be created, but if chosen to create it is not created though connection for super user is checked.
* Unable to provide anonymous user
* If user changes his mind and would like to not provide password then in some cases he is unable as there is no way to figure out if he wants to use default or empty password
* DSN for provided user is not verified
* Sometimes password was in plain-text (because of defaults)
never mind - I've figure out this (or at least I think so)