I tried to install Fiware IDM in Ubuntu 12.04 from scratch (just only Ubuntu 12.04 was installed, no any more packages). I have followed the guide https://github.com/ging/fi-war
For development purposes, change this variable from
OPENSTACK_KEYSTONE_URL = "https://%s:5000/v3" % OPENSTACK_HOST to OPENSTACK_KEYSTONE_URL = "http://%s:5000/v3" % OPENSTACK_HOST
inside idm/horizon/openstack_dashboard/loca/local_settings.py (arround 130th line)