HTTP link header parser needed

[edwardsph]

There can be 1 or more Link headers in a response (e.g. CSS, ESS) and a link header can contain 1 or more links (e.g. NSS). We need a parser that will handle both format (and technically a mix of them). The current solution assumes one or the other method is used and when it encounters a multi-value link header it does a simple split on , . This was adequate to get started but it since a comma can appear within a link definition, we need a proper parser for this.