Change TastytradeAuth to receive base url as an argument to allow for cert environment

[cskolaut]

When testing/developing against the TastyTrade API, you should be able to use the https://api.cert.tastyworks.com URL.
Allow for authenticating against the cert environment

[peter-oroszvari]

Thanks for the suggestion, will implement soon.

[peter-oroszvari]

I've just updated the init.py in the root folder, added a variable, and updated the URLs of authentication.py