implement deleted posts cleanup, extend sync response features

src/response.rs

@@ -0,0 +1,14 @@
+#[derive(Default)]
+pub struct Deleted {
+    pub files: usize,
+    pub directories: usize,
+}
+
+#[derive(Default)]
+pub struct Response {
+    pub created: usize,
+    pub deleted: Deleted,
+    pub ignored: usize,
+    pub total: usize,
+    pub updated: usize,
+}