Show diff for changed scope

[jdevries3133]

This is a draft PR to show a clean diff instead of a "splat" of text when a scope
change occurs. According to (my understanding of) RFC 6749 Section A.4, the only
allowed delimiter for oauth scopes is a space character:

A.4.  "scope" Syntax

   The "scope" element is defined in Section 3.3:

     scope       = scope-token *( SP scope-token )
     scope-token = 1*NQCHAR

Therefore, this implementation should be good to go. I updated tests so that
they pass with the change. Looking forward to feedback.

Please note that there could be a possible merge conflict with pr#810, so please
review and merge that less-controversial PR first so that I can resolve those
changes into this draft.

Thanks!