Update CocoaLumberjack 1.6.2


* Deduce tag from Pod version.
* Fix `pod spec lint` warnings.
* Remove files not directly related to the static library (Benchmarking, Demos) as Pods normally do.
* Add platform requirements (https://github.com/robbiehanson/CocoaLumberjack/issues/116).

Related to https://github.com/robbiehanson/CocoaLumberjack/issues/143 .