Fixed asynchronous Activity leaks in Fragments

If a Fragment has been detached its getActivity() method will return null, providing numerous crash possibilities within the app.

My approach to fixing this is to make Fragments use their own runOnUiThreadUnlessDestroyed method, which also checks if the Fragment has been detached before running the Runnable

Closes #714 (closed)

briar-android/src/org/briarproject/android/blogs/BlogFragment.java

@@ -47,7 +47,7 @@ import static org.briarproject.android.blogs.BlogActivity.REQUEST_WRITE_POST;
 public class BlogFragment extends BaseFragment implements
 		OnBlogPostAddedListener {
 
-	public final static String TAG = BlogFragment.class.getName();
+	private final static String TAG = BlogFragment.class.getName();
 
 	@Inject
 	BlogController blogController;
@@ -178,7 +178,7 @@ public class BlogFragment extends BaseFragment implements
 	public void onBlogPostAdded(BlogPostHeader header, final boolean local) {
 		blogController.loadBlogPost(header,
 				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						listener) {
+						this) {
 					@Override
 					public void onResultUi(BlogPostItem post) {
 						adapter.add(post);
@@ -201,10 +201,10 @@ public class BlogFragment extends BaseFragment implements
 		);
 	}
 
-	void loadBlogPosts(final boolean reload) {
+	private void loadBlogPosts(final boolean reload) {
 		blogController.loadBlogPosts(
 				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
-						listener) {
+						this) {
 					@Override
 					public void onResultUi(Collection<BlogPostItem> posts) {
 						if (posts.isEmpty()) {
@@ -225,7 +225,7 @@ public class BlogFragment extends BaseFragment implements
 
 	private void loadBlog() {
 		blogController.loadBlog(
-				new UiResultExceptionHandler<BlogItem, DbException>(listener) {
+				new UiResultExceptionHandler<BlogItem, DbException>(this) {
 					@Override
 					public void onResultUi(BlogItem blog) {
 						setToolbarTitle(blog.getBlog().getAuthor());
@@ -299,7 +299,7 @@ public class BlogFragment extends BaseFragment implements
 
 	private void deleteBlog() {
 		blogController.deleteBlog(
-				new UiResultExceptionHandler<Void, DbException>(listener) {
+				new UiResultExceptionHandler<Void, DbException>(this) {
 					@Override
 					public void onResultUi(Void result) {
 						Toast.makeText(getActivity(),