Add database export/import command

[philipnewcomer]

It would be nice to have a command to do a bulk export or import of all MySQL databases. The databases could be saved to the individual site directories (alongside the config.yml file which may already exist), and should be able to be exported/imported on a site-by-site basis or a global (all sites) basis.

[AaronHolbrook]

Yes. Please.

[philipnewcomer]

also create/drop/reset