Add Statistics Actor
Add commands for showStats
Refactor Persistence
Add Statistics Actor
Add commands for showStats
Refactor Persistence

Conflicts:
	WebCrawlerAKKA/src/main/java/com/en_workshop/webcrawlerakka/akka/actors/domain/DomainActor.java
	WebCrawlerAKKA/src/main/java/com/en_workshop/webcrawlerakka/akka/actors/domain/DomainMasterActor.java
	WebCrawlerAKKA/src/main/resources/application.conf