ZF-7924: BC Break in Zend_Db::factory()

Description

As noted on fw-general and #zftalk.dev, 1.9.3 introduces a BC break in regards to the documented (per API, not manual) behavior of Zend_Db::factory(), namely that the argument is case sensitive. The break should be reverted, while still supporting the fix for the adapter namespace case insensitivity.

Comments

Fixed in trunk at r18372 and in branch release 1.9 at r18373