Crash when running example

[git-commit]

• webexteamsbot version: 0.1.2.1
• Python version: 3.7
• Operating System: Windows

Description

1. Make a new Virtualenv
2. Install the library
3. Try to run the example

What I Did

Running the provided sample results in the following stacktrace:

Traceback (most recent call last):
  File "bot.py", line 15, in <module>
    teams_bot_email=bot_email,
  File "C:\Users\Max\Envs\w\lib\site-packages\webexteamsbot\webexteamsbot.py", line 43, in __init__
    super(TeamsBot, self).__init__(teams_bot_name)
  File "C:\Users\Max\Envs\w\lib\site-packages\flask\app.py", line 371, in __init__
    root_path=root_path
  File "C:\Users\Max\Envs\w\lib\site-packages\flask\helpers.py", line 891, in __init__
    root_path = get_root_path(self.import_name)
  File "C:\Users\Max\Envs\w\lib\site-packages\flask\helpers.py", line 735, in get_root_path
    loader = pkgutil.get_loader(import_name)
  File "c:\python37\Lib\pkgutil.py", line 479, in get_loader
    return find_loader(fullname)
  File "c:\python37\Lib\pkgutil.py", line 489, in find_loader
    if fullname.startswith('.'):
AttributeError: 'NoneType' object has no attribute 'startswith'

[DockCZ]

Hi have entered environment variables?

export TEAMS_BOT_URL=https://mypublicsite.io
export TEAMS_BOT_TOKEN=
export TEAMS_BOT_EMAIL=
export TEAMS_BOT_APP_NAME=

or for me also works editing the code:
bot = TeamsBot( "<your bots name>", teams_bot_token="<your bots token>", teams_bot_url="https://mypublicsite.io", teams_bot_email="<your bots email>",)