Revert addition of write_db directly to the Horde_Db_Adapter_Base object, along

Revert addition of write_db directly to the Horde_Db_Adapter_Base object, along
with executeWrite() which is unnecessary at this level.

Revert "Add ability to define a write DB for use with split-DB installations"

This reverts commit 0c369fee9b6ef70bdd92f1141635699d5ad9707b.

Conflicts:

	framework/Core/lib/Horde/Core/Binder/Db.php
	framework/Db/lib/Horde/Db/Adapter/Base.php
	framework/Db/package.xml

Revert "Add executeWrite()."

These queries should always go to the write db

This reverts commit 556ca7c259f179d69a1bace18224280720889acc.

Conflicts:

	framework/Db/lib/Horde/Db/Adapter/Base.php

remove executeWrite() calls from Oracle schema