#437 Email uniqueness in admin command; finalization

- Check also in admin command that email is not already used
- Misc bug fixing (logic errors, changes lost during large merge)
- Use "email" and "setemail" as main labels for /authme subcommands

src/test/java/fr/xephi/authme/process/email/AsyncAddEmailTest.java

@@ -187,7 +187,7 @@ public class AsyncAddEmailTest {
         dataSource = mock(DataSource.class);
         playerCache = mock(PlayerCache.class);
         settings = mock(NewSetting.class);
-        return new AsyncAddEmail(authMe, player, email, dataSource, playerCache, settings);
+        return new AsyncAddEmail(player, authMe, email, dataSource, playerCache, settings);
     }
 
 }