[Shtoom] remove unused import

[zooko at zooko.com]

HACK pion:~/playground/shtoom$ darcs annotate -u --patch="remove unused import"
[remove unused import
zooko at zooko.com**20040903111834] 
<
> {
hunk ./shtoom/shtoom/sip.py 19
 from twisted.internet import defer
 from twisted.internet import reactor
 from twisted.protocols import sip as tpsip
-from rtp import RTPProtocol
 
 import shtoom
 from shtoom import __version__ as ShtoomVersion
}