add default empty value to get user agent in session
Don't show traceback when sending ^C during runserver refs #54

% python decanter.py runserver

==================================================
Welcome to Decanter!
You're ready to go!
Server running on http://localhost:9000
==================================================
^C
Good-bye!
Merge pull request #55 from narusemotoki/develop

Don't show traceback when sending ^C during runserver refs #54
fix session object not getting create on each request
Small update
Merge branch 'master' of https://github.com/gengo/decanter