Refactor getPosts() to use template request

Sources/WriteFreely/WFClient.swift

@@ -255,17 +255,9 @@ public class WFClient {
         request.addValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
         request.addValue(tokenToVerify, forHTTPHeaderField: "Authorization")
 
-        let dataTask = session.dataTask(with: request) { (data, response, error) in
-            // Something went wrong; return the error message.
-            if let error = error {
-                completion(.failure(error))
-            }
-
-            if let response = response as? HTTPURLResponse {
-                guard let data = data else { return }
-
-                // If we get a 200 OK, return the WFUser as success; if not, return a WFError as failure.
-                if response.statusCode == 200 {
+        get(with: request) { result in
+            switch result {
+            case .success(let data):
                 do {
                     // The response is formatted differently depending on if we're getting user posts or collection
                     // posts,so we need to determine what kind of structure we're decoding based on the
@@ -280,17 +272,12 @@ public class WFClient {
                 } catch {
                     completion(.failure(error))
                 }
-                } else {
-                    // We didn't get a 200 OK, so return a WFError.
-                    guard let error = self.translateWFError(fromServerResponse: data) else { return }
+            case .failure(let error):
                 completion(.failure(error))
             }
         }
     }
 
-        dataTask.resume()
-    }
-
     /// Moves a post to a collection.
     ///
     /// - Attention: ⚠️ **INCOMPLETE IMPLEMENTATION** ⚠️