set initial site data via data migration

- change example.org site to configurable domain and site name values
- add environment variable COFFEESTATS_DOMAIN_NAME to .travis.yml, csdev.sh and
  coffeestats.uwsgi.ini
- add data migration caffeine.migrations.0002_create_domain
- initialize site name and domain name in coffeestats.settings.base
- add pillar data for vagrant VM