#9 HTTPS WCAP : ask the user what to do with invalid server cer

[Sebastien Stormacq]

Current version ignores the server certificate
verification status. This means that the Calendar
Server might use an expired, self-signed or otherwise
invalid certificate.

Although great for accessing some servers, this feature
must be controlled by the end user.

Currently, JSCalendarSync accepts all certificates,
including invalid ones.

In such a case, the user should be prompted with a
message asking him what to do : continue or abort.