add cli ryu application

this consists of:
- a simple internal management api (management.py)
- a user interface backend (cli.py)

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
cli: require telnetsrv

add telnetsrv to pip-requires.

unfortunately there seems to be no RPM equivalent available.
if you want to use cli.py, install telnetsrv by yourself for now.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
ryu-manager: stop modifying CONF.app_list

to make cli show-options a little prettier.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>