Catch token expiry

[whelks-chance]

Copy/paste this:

https://github.com/SIMBAChainDev/simba-etl-upload-utils/blob/master/upload_utils.py#L11

If reading from file, check not expired, otherwise renew.
When writing to file, write expiry datetime too.

[abrinckm]

@whelks-chance will do. I'll see if I can get this working tonight

[whelks-chance]

I've pushed an update to this, tokens are now in file and memory, and expiry is detected.