Add support example/examples on content value body request

[thaichat04]

From #86:

• add example/examples on content Body Request
• make attributs are optional

[manchenkoff]

Hey @thaichat04, thanks a lot for the contribution! However, there are some failing tests since you extended the data class. Please, take a look and we are ready to go!

[thaichat04]

Thanks, I didn't see tests failed. Sorry

[manchenkoff]

Thanks, I didn't see tests failed. Sorry

There are still some errors after your last commit:

ERROR tests/test_parser.py - TypeError: __init__() missing 1 required positional argument: 'example'
ERROR tests/test_runner.py - TypeError: __init__() missing 1 required positional argument: 'example'
ERROR tests/builders/test_content_builder.py - TypeError: __init__() missing 1 required positional argument: 'example'
ERROR tests/builders/test_request_builder.py - TypeError: __init__() missing 1 required positional argument: 'example'

you can run them locally via

pipenv run python setup.py install
pipenv run pytest