Add warn method back to LogAdapter
Add warn method back to LogAdapter

The change in 684c4c04 to improve py3 support breaks older middleware
that consumes the SwiftLogger.

Good for Swift code to not to use warn because it's deprecated.

Bad for LogAdapter to not faithfully provide the current python logging
module API (deprecated or otherwise).

Change-Id: Ib0baf66b7f33f91562867076ff0526a287d8e5a6

openstack/swift,revoer/keystone-8.0.0,hurricanerix/swift,clayg/swift,nadeemsyed/swift,hurricanerix/swift,clayg/swift,swiftstack/swift,psachin/swift,clayg/swift,openstack/swift,redbo/swift,larsbutler/swift,williamthegrey/swift,matthewoliver/swift,notmyname/swift,aerwin3/swift,hurricanerix/swift,nadeemsyed/swift,prashanthpai/swift,smerritt/swift,openstack/swift,tipabu/swift,tipabu/swift,prashanthpai/swift,redbo/swift,notmyname/swift,clayg/swift,smerritt/swift,smerritt/swift,psachin/swift,williamthegrey/swift,notmyname/swift,psachin/swift,nadeemsyed/swift,matthewoliver/swift,nadeemsyed/swift,larsbutler/swift,openstack/swift,aerwin3/swift,smerritt/swift,swiftstack/swift,matthewoliver/swift,tipabu/swift,notmyname/swift,swiftstack/swift,matthewoliver/swift,revoer/keystone-8.0.0,tipabu/swift,hurricanerix/swift,psachin/swift