This PR add users and users auth to kiskadee API, the auth can use an e-mail confirmation or not based on a configuration.

For the user API and auth the following environment variables are used:
For the user auth:
* TOKEN_SECRET_KEY for user auth token, default: "default development key" for dev

For the email confirmation:
* EMAIL_TOKEN_SECRET_KEY for mail confirmation token, default "dev email token" for dev
* MAIL_USERNAME the mail server username
* MAIL_PASSWORD the mail server password

By default the email confirmation feature is disabled for dev purpose, but it can be enabled by setting MAIL_ENABLED=True on the "kiskadee.conf" file.
Also was added on the "kiskadee.conf" file others mail configs values.

Summary, when going on production set TOKEN_SECRET_KEY, MAIL_ENABLED=True, EMAIL_TOKEN_SECRET_KEY, MAIL_USERNAME and MAIL_PASSWORD.
If on development, just let it to its default values.