added needed fields in models and needed libraries for frontend (#67)

src/main/java/com/commafeed/backend/model/FeedCategory.java

@@ -35,6 +35,8 @@ public class FeedCategory extends AbstractModel {
 
 	private boolean collapsed;
 
+	private Integer position;
+
 	public String getName() {
 		return name;
 	}
@@ -86,4 +88,12 @@ public class FeedCategory extends AbstractModel {
 		this.collapsed = collapsed;
 	}
 
+	public Integer getPosition() {
+		return position;
+	}
+
+	public void setPosition(Integer position) {
+		this.position = position;
+	}
+
 }

src/main/java/com/commafeed/backend/model/FeedSubscription.java

@@ -33,6 +33,8 @@ public class FeedSubscription extends AbstractModel {
 	@OneToMany(mappedBy = "subscription", cascade = CascadeType.REMOVE)
 	private Set<FeedEntryStatus> statuses;
 
+	private Integer position;
+
 	public Feed getFeed() {
 		return feed;
 	}
@@ -73,4 +75,12 @@ public class FeedSubscription extends AbstractModel {
 		this.statuses = statuses;
 	}
 
+	public Integer getPosition() {
+		return position;
+	}
+
+	public void setPosition(Integer position) {
+		this.position = position;
+	}
+
 }

src/main/java/com/commafeed/backend/services/FeedSubscriptionService.java

@@ -5,6 +5,8 @@ import java.util.List;
 import javax.ejb.ApplicationException;
 import javax.inject.Inject;
 
+import org.apache.commons.lang.StringUtils;
+
 import com.commafeed.backend.dao.FeedEntryDAO;
 import com.commafeed.backend.dao.FeedEntryStatusDAO;
 import com.commafeed.backend.dao.FeedSubscriptionDAO;
@@ -50,7 +52,7 @@ public class FeedSubscriptionService {
 			FeedCategory category) {
 
 		final String pubUrl = applicationSettingsService.get().getPublicUrl();
-		if (pubUrl == null) {
+		if (StringUtils.isBlank(pubUrl)) {
 			throw new FeedSubscriptionException(
 					"Public URL of this CommaFeed instance is not set");
 		}