Add :password_for_default_users to dev sample settings
Update readme: probe_config, solr, create_default_data

Added instructions for load_probe_configurations and for
starting solr.

Replaced app:setup:new_app with app:setup:create_default_data,
Note that this requires `:password_for_default_users: password`
to be added to settings.yml.

Also switched suggested RAILS_ENV to development, per scytacki's
suggestion.