Remove blog as well when removing RSS feed

This also adds a confirmation dialog to the removal process.

briar-api/src/main/java/org/briarproject/briar/api/blog/BlogManager.java

@@ -41,6 +41,11 @@ public interface BlogManager {
 	 */
 	void removeBlog(Blog b) throws DbException;
 
+	/**
+	 * Removes and deletes a blog with the given {@link Transaction}.
+	 */
+	void removeBlog(Transaction txn, Blog b) throws DbException;
+
 	/**
 	 * Stores a local blog post.
 	 */

briar-api/src/main/java/org/briarproject/briar/api/feed/FeedManager.java

@@ -23,7 +23,7 @@ public interface FeedManager {
 	/**
 	 * Removes an RSS feed.
 	 */
-	void removeFeed(String url) throws DbException;
+	void removeFeed(Feed feed) throws DbException;
 
 	/**
 	 * Returns a list of all added RSS feeds