Accept-Additions Header non-compliant with RFC2324

[scott181182]

The stored responses with an Accept-Additions header incorrectly delimits additions with semicolons, when semicolons [";"] should be used per addition to denote additional "params" (see relevant section of RFC2324) or "accept-params" (see relevant section of RFC2616). While RFC2324 doesn't explicitly denote a separation character, a comma [","] is standard use for HTTP header ranges.