Update README.md
replaced usages of getUser(String) and similar with UUID version when possible
UserBase now uses UUID instead of String
fixed missing Unique index creation on user table update
Merge branch 'origin/master'

Conflicts:
	log/src/main/java/de/cubeisland/engine/log/action/logaction/kill/KillActionType.java
	log/src/main/java/de/cubeisland/engine/log/storage/LogEntry.java