[reSIProcate] SRV lookup problem

[Jason Fischl]

It seems that the DNS SRV lookup code is hardcoding to use the _SIP scheme.
In general the scheme of the target uri should be used instead of _SIP. For
example, a target of pres:jason at example.com should result in an SRV query to
_PRES._UDP.example.com. Are there any examples where this is not the case?

I'll try and make this change tomorrow.

Jason