This is due to keystone is not getting started properly and therefore port 35357 is not in listening mode.
This seems to be anomalous behavior of service keystone.
I am mentioning steps which have worked on my system for havana installtion on Ubuntu 12.04 Kernel version 3.2.0-67-generic. After a day of headache around this issue. Try these steps, preferably in the same order.
1) Remove keystone package:-
apt-get remove keystone
2) Reboot your system
3) After reboot again INSTALL KEYSTONE.
apt-get install keystone
4) Check status of keystone service
service keystone status
It will show start/running
5) Now do the necessary changes you want to do in /etc/keystone/keystone.conf
after making changes in conf file DO NOT RESTART KEYSTONE SERVICE
Use stop and start command to make an effect of restart but don't restart.
service keystone stop
service keystone start
For further help, pasting a dump of my CLI :-