Migrate avatars and group avatars.

app/src/main/java/org/thoughtcrime/securesms/util/FileUtils.java

@@ -49,13 +49,13 @@ public final class FileUtils {
     }
   }
 
-  public static void deleteDirectory(@Nullable File directory) {
+  public static boolean deleteDirectory(@Nullable File directory) {
     if (directory == null || !directory.exists() || !directory.isDirectory()) {
-      return;
+      return false;
     }
 
     deleteDirectoryContents(directory);
 
-    directory.delete();
+    return directory.delete();
   }
 }

app/src/main/java/org/thoughtcrime/securesms/util/Util.java

@@ -224,7 +224,9 @@ public class Util {
     }
   }
 
-  public static void close(Closeable closeable) {
+  public static void close(@Nullable Closeable closeable) {
+    if (closeable == null) return;
+
     try {
       closeable.close();
     } catch (IOException e) {
@@ -607,4 +609,12 @@ public class Util {
     return concat;
   }
 
+  public static boolean isLong(String value) {
+    try {
+      Long.parseLong(value);
+      return true;
+    } catch (NumberFormatException e) {
+      return false;
+    }
+  }
 }