[Submodule] add git submodule 'khttp' and 'parson'

khttp:
https://github.com/kaija/khttp

parson:
http://kgabis.github.io/parson/
https://github.com/kgabis/parson
add Makefile and initialize the folder architecture

.
├── Makefile
├── README.md
├── lib
│   ├── khttp
│   └── parson
├── src
│   ├── sm_api.c
│   └── sm_api.h
└── test
    ├── Makefile
    └── user_api.c
implement sm_user_digest_login API