Remove max.connections from requirements for dbGetInfo(Driver)

[krlmlr]

Instead of dbGetInfo(Driver) entry.

[hadley]

Actually I think max connections should go away altogether - it's an artefact of the older style of implementing backends.

[hannes]

@hadley +1.

[hannes]

I am not sure in general what the purpose of the getInfo functions is and who actually uses those.

[krlmlr]

At the very least, this allows a general-purpose implementation of show().

[hannes]

Yes but which properties are used there?

[krlmlr]

The help for dbGetInfo() has a "wish list". We can start from that, and DBItest would test those, too. See also #54

[hadley]

I think it would be better to provide an extremely basic show method in DBI, and then assume backend authors will provide richer methods.