fix: dev: 优化Flask语法 & 修正Flask找不到templates文件夹的问题

1.
优化Flask语法，使用flask自带的jsonify进行json回复；使用flask自带的render_template进行html模版回复；
简化Flask书写语法
2. 将server文件夹更名flask_templates，在Flask初始化时将模版文件夹路径指向此文件夹

wxbot_project_py2.7/config/constant.py

@@ -23,8 +23,8 @@ class Constant(object):
     
     SERVER_LOG_FORMAT = '%(asctime)s - %(pathname)s:%(lineno)d - %(name)s - %(levelname)s - %(message)s'
     SERVER_UPLOAD_ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])
-    SERVER_PAGE_UPLOAD = 'Server/upload.html'
-    SERVER_PAGE_INDEX = 'Server/index.html'
+    SERVER_PAGE_UPLOAD = 'upload.html'
+    SERVER_PAGE_INDEX = 'index.html'
 
     RUN_RESULT_SUCCESS = '成功 %ds\n'
     RUN_RESULT_FAIL = '失败\n[*] 退出程序\n'