Implement $dbh->{Name}

Low priority.

Per DBI POD, database handles should have an attribute named `Name`, which is a representation of the connected database (typically the _db=foobar_ part of `dbi:Foo:db=foobar;...`).

This patch adds support for that driver-supplied attribute and a test case.  (Actually, it adds several test cases for common `$dbh` attributes, but by no means an exhaustive suite.)

*Prior Behavior*
```perl
$dbh->{Name};   # Can't get DBI::db=HASH(0xf00dd00f)->{Name}: unrecognised attribute name at ... line ...
```
*New Behavior*
```perl
$dbh->{Name};   # 'db=/tmp/dbd-fb-testdb.fdb'
```