DDLogMessage conforms to NSCopying to allow copy operation
Added DD preffix to extension classes (ContextFilterLogFormatter and DispatchQueueLogFormatter)
Added DDMultiFormatter (allows chaining formatters)
Updated Custom Log Levels example due to the addition of DEBUG log level (The issue was spotted by a Koen Dierckx and reported here: https://groups.google.com/forum/#!topic/cocoalumberjack/gZavD3wxXUw)
Reverted NSLog to NSLogVerbose (https://github.com/robbiehanson/CocoaLumberjack/pull/174/files#r7923632)
Merge pull request #178 from bpoplauschi/DDMultiFormatter_and_extensions_preffix

DDMultiFormatter and extensions preffix