Tags are optional but roboswag fails on missing tags

[bhirsz]

Editied - I was under wrong impression how the code works. We're parsing the endpoints and then using tag attribute to store them in unique list. If the tags are missing, the code will fail. It still requires deeper analysis.

[bhirsz]

If the tags are missing, we will now generate endpoint class names from API paths. The first part of the path will become endpoint class name (for example GET /users/user will become Users.py with def get_user() method).