ILogger interface added

* ILogger interface extends ILoggerBase and ISuppress. At the moment, it is not CLS compliant because of the V1 interface methods.
* ILoggerBase exposes the basic Log() methods.
* ISuppress interface added. It contains the Swallow() and SwallowAsync() methods definitions. Provides an interface to execute System.Actions without surfacing to the calling method any exceptions raised for that action.