fix for sf#2971422 - SIP URI case mismatch

fix for sf#2971422 - SIP URI case mismatch
affected 2005 platform.
On some 2005 environments server for some strange
reasons inverts case of SIP URI compare to the one
set in our account settings.

From the bug comments:
"It looks
like the server plays games with us.

If we configure username in account settings in lowercase (like
first_last@bbb.com in your case), it send us presence updates with first
letters of first and last names capitalized (like First_Last@bbb.com).

But If we configure username in account settings with first letters of
first and last names capitalized (like First_Last@bbb.com), it send as
presence updates in lowercase (like first_last@bbb.com).

Check this string in logs yourself :)
<resource uri="sip:First_Last@bbb.com" > (substituting to the real values
for your account of course first)."