[reSIProcate] DIGEST - case sensitive?

[Daniel Pocock]

I've just discovered the following comparison in several places in 
Helper.cxx:

            if(i->scheme()!="Digest")
            {
               continue;
            }

Unfortunately, this is case sensitive and breaks compatibility with my 
Budgetone, which is sending DIGEST and not Digest

Nothing is logged, except a message about `invalid nonce'

SIP/2.0 403 Invalid nonce.

Is it sufficient for me to replace this code with strcasecmp, or is 
something more elegent required to support other character sets?

Regards,

Daniel