save token to environment

[schochastics]

See discussion #15 (comment)

[JBGruber]

Not sure if it makes more sense to save the token or the token location as the env variable. The token consists of 3 relevant parts: bearer, instance and type. These could go into one env variable, but we would need to also parse it then. Or they go into 3 variables, which seems a bit clumsy to me.

I would say the file and path in the variable approach is cleaner. But maybe we need the whole token for testing (#19)?

[chainsawriot]

@JBGruber Not in a straight sense. The envvar RTOOT_DEFAULT_TOKEN is for filtering out the sensitive information (i.e. the token) when creating vcr cassettes. It won't need for testing.

[chainsawriot]

GOTO #68