Allow use of API Key instead of account credentials

[jstuyts]

Currently only the account SID and auth token can be used to authenticate with Twilio. It would be nice if an API Key could also be used so access to the account can be revoked without having to close the account.

[legrego]

Thanks for opening this issue - good suggestion. I don't have as much time as I'd like to work on this these days, but I'll definitely consider adding this the next time I open up this project.

I've mostly moved on to home-assistant given its recent stability improvements, so I don't personally rely on HomeSeer as much as I used to for my own setup.