完成HTTP解析请求侧解析基本流程

* 集成HTTP Parser，解析HTTP请求侧数据；
* 增加tfe_http.h中请求方法、应答状态的常量定义
* 变更tfe_http.h中HTTP头部标准定义，去掉非头部字段，增加TFE前缀避免冲突。

plugin/protocol/http/CMakeLists.txt

@@ -1,4 +1,8 @@
 
-add_library(http src/http.cpp)
+add_library(http src/http_entry.cpp src/http_half.cpp)
+target_include_directories(http PRIVATE include/internal)
+target_include_directories(http PUBLIC incluce/external)
+
 target_link_libraries(http common)
 target_link_libraries(http http-parser-static)
+target_link_libraries(http libevent-static)