code: public Long postCreate(String blogName, Map<String, ?> detail) throws IOException {
          return requestBuilder.postMultipart(JumblrClient.blogPath(blogName, "/post"), detail).getId();
      }
docs: Create a post
  @param blogName The blog name for the post
  @param detail the detail to save
  @return Long the created post's id
  @throws IOException if any file specified in detail cannot be read