add multiple choose for features.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
add detect feature function.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
fixed features not defined.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
You can choose some feature what you want.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update unit test

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Merge pull request #6 from appleboy/feature/choose_features

feature: choose some features