User shouldn't have to link their account in order to browse the marketplace.
Don't need the "Link Account" notification any more
Let users view add-on Details even when not authenticated via OAuth2
Use Sputnik::account_is_linked() to check for linking status
Let user resume Purchase flow after OAuth2 authentication
Merge PR #632

Fixes #631
Closes #632
small bugfix for NL language
Add no_variation message for when combination of variants is not available.
Merge PR #628

Closes #628