Better support of multiple connections

[willdurand]

Hi there,

So basically, I think it could be nice to improve create/drop commands
to handle multiple connections. Thing is, create only creates the database
for the default connection, which is not cool if you expect the command
to create all databases for all connections.

I think we should loop over the connections and create each database. Same
thing for the drop command.

WDYT?

[jaugustin]

👍
and also adding option for choosing default charset ;)

[jaugustin]

@willdurand I would also add alias connection settings to overwrite bundle connection name on the fly.
This allow to use external bundle that use connection name not default or when you use multiple connection and don't to duplicate schema.xml to only change connection name.