Add NSLOGGER_WAS_HERE as preprocessor macro for Cocoapods

When using CocoaPods, NSLOGGER_WAS_HERE is now included
as preprocessor macro in the project settings. This allows
other pods to recognize NSLogger and react to its
presence.
Merge pull request #109 from mkauppila/cocoapods-fix

Add NSLOGGER_WAS_HERE as preprocessor macro for Cocoapods