allow empty values
django 1.4 compatibility
remove unused import
django 1.4 depreciation
option to allow non-superusers to update settings
add Polish translation
1.5 compatibility‎ (meta.swapped)
Merge branch 'master' of git://github.com/qois/django-constance
Merge branch 'master' of git://github.com/jerzyk/django-constance
comoga/django-constance#14 allow empty strings

this changes to default configuration to using a dictionary instead of a 2-tuple
so we can provide much more and richer information about settings. the two tuple
is still supported.

the configuration will now be checked at startup time and will raise ImproperlyConfigured
when an error is found.