Use native quote attribute introduced in sqla 0.9

In SQLA 0.9 there is now a native .quote attribute on many objects.
Conditionally use this instead of the old method if the attribute
exists, to remove deprecation messages (and prepare for when the
other way will be fully removed).

Change-Id: I3c5fada13e044c1c4102acc0455226ce1524f2e2