[Shtoom] hangup patch

[Aaron Zinman]

I don't know the experience of others, but I have found with 2  
different sip providers putting the local tag on the from field in a  
BYE sent from Shtoom produces an unknown dialog error.  I have a  
hacky patch which gets rid of it there for file shtoom/sip.py:

739c739,741
<         bye.addHeader('from', str(self.dialog.getLocalTag()))
---
 >         # get rid of ;tag=xxxx bit to satisfy sipphone (and others?)
 >         localTag = str(self.dialog.getLocalTag())
 >         bye.addHeader('from', localTag[:localTag.find(';')])


This seems to make the other side happy (sipphone/asterisk & another  
provider w/a proprietary stack).

--Aaron