Update DDLog.m
"Fix" conflicts with 3rd party libraries using CocoaLumberjack

As discussed in #162, there's no solution to sharing `ddLogLevel` between libraries and the client application:

* Apps/libraries may define `ddLogLevel` as a const, extern, int, a function returning an int, etc. Each one incompatible with the other.

* Even more, if apps/libraries used a compatible and shared `ddLogLevel` there would be no way to manage separately log levels from each one.

The solution is to define a `LOG_LEVEL_DEF` by default equal to `ddLogLevel` so apps can continue to work as usual.

3rd party libraries simple redefine `LOG_LEVEL_DEF` to something different:

```obj-c
// #undef LOG_LEVEL_DEF // Undefine first only if needed
#define LOG_LEVEL_DEF myLibLogLevel
```

3rd party frameworks **need** to be updated.
Merge pull request #172 from rivera-ernesto/fix_ddloglevel_conflict

"Fix" conflicts with 3rd party libraries using CocoaLumberjack
Update podspec
Better Device version detection

Changed to NSFoundationVersionNumber_iOS_6_0
Update DDLog.m
Merge pull request #171 from mojtabacazi/patch-1

Update DDLog.m
Allow customizing the naming convention for log files to use timestamps.

We find UUIDs to quite awkward in the field because the files cannot be
sorted in chronological order by filename. This patch adds an optional
convention to the DDLogFileManagerDefault class which uses timestamps
instead. The existing UUID-based naming convention is retained as the
default convention for backwards compatibility.

Timestamps are formatted as RFC 3339 dates in the UTC time zone.
Merge pull request #174 from toushay/master

Allow customizing the naming convention for log files to use timestamps.
Modernize -creationDate for iOS

It also fixes the getattrlist bug on 64-bit system.
Merge pull request #177 from an0/master

Modernize -creationDate for iOS
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
Moved DDLog+LOGV.h file to the Lumberjack folder where it gets picked up by Cocoapods
Tabs changed to spaces in Lumberjack and Xcode directories
Merge pull request #180 from dvor/master

Tabs changed to spaces in Lumberjack and Xcode directories