MBSF: Stop wrapping Content-Location values in literal quote characters

[davidjwbbc]

@jordijoangimenez writes:

RFC 2557 §4.1 defines Content-Location as a bare URI-reference, with no quoted-string form -- writing Content-Location: "announcement.json" makes the quote characters part of the value itself.

[davidjwbbc]

If you go on to read Section 4.4 in RFC 2557, which indicates how to "fold" a URI that contains other characters or that is too long for an RFC 822 header, it does allow the URI to be quoted and folded and therefore the value should be unfolded/unquoted before being used.

[davidjwbbc]

Although the original premise of this issue is incorrect, there is still a bug in that the quoted strings are not escaped for \ and " characters. This escaping needs to be done to implement this properly.

[rjb1000]

@jordijoangimenez: @davidjwbbc will provide a fix from scratch for this bug since your originally proposed solution was not correct.