Installer – run database build in separate steps

[mbohal]

During installation and update process the db creation and migration tasks can take too long and then there can be PHP or webserver timeout.

The PHP timeout was hackishly solved by disabling it in the script, but there is no clean way to deal with the webserver timeout. The present situation therefore is that if the user disregards the webserver timeout and keeps on waiting, then the PHP script will likely eventually finish on the background and all will be OK. Of course the PHP script could be killed by the OS and the user has no way of knowing other then trying the installation out.

Ideally the db creation and migrations should be run in separate requests that will be triggered sequentially. JS could probably do this. Using JS would also make it reasonably easy to provide the user with a nice progress report.