Expansion logging method

[iGabyTM]

Add a method to log stuff to console (similar to getLogger() from JavaPlugin) and have [{expansion identifier} Expansion] as prefix, after PAPI's prefix. Eg. [PlaceholderAPI] [Statistic Expansion] X is not a valid statistic

[PiggyPiglet]

a logger will be injectable, e.g. @Inject private Logger logger;