Standardize api for scopes

[jamiefolson]

Facebook scopes are supposed to be comma-separated. Google scopes are space-separated. Currently, velruse just assumes you know this and have properly formatted the scope string. It'd be great to not have to know this.

[jamiefolson]

My idea would be to maintain backwards-compatibility by simply allowing the scope parameters to be passed as a list, which is then correctly formatted by velruse.

[mmerickel]

I think the supported options could be standardized but they'd have to remain strings because the scope can usually also be specified in the POST request to the login url (not just the settings). With that in mind, comma-separated would be good as long as it doesn't break google's scopes.