Revert "Add Horde_Mongo_Exception"

This reverts commit 591ab423f6d9766b5b30d1f94d735cde9589ab19.

This change is BC breaking, and needs to wait until Horde_Mongo 2.0.
Revert "Bump minimum version, catch Exceptions."

This reverts commit 395fdc4a69f2cb0f228b975ebc54757624c2266e.
Revert "Catch Horde_Mongo_Exception"

This reverts commit facf7da6efbc0cbab8221f7016159efdeeaf80f0.
Revert "Catch Horde_Mongo_Exception"

This reverts commit eaa3990898b6770e6a4f1c87b110ea90f8995d7c.