Expiration time fix

Now fetches seconds correctly from a datetime.timedelta instance

Thanks to @Przemoo16 for the fix

Base64 Encoding

This implements a flag that let you specify whether you want to have a token be base64 encoded, as well as whether a token that gets checked should be base64 decoded.

Custom Token Types

You can now create tokens with a custom type

v0.5.1

Update coveralls command