Fixed one typo in response_helpers which caused is_admin context variable not to work correctly. Created new checkLinkNameForId function that checks if link_name is correct when creating new user and modifying existing one. This is now used for validation instead of doesLinkNameBelongToId in UserForm clean_link_name function. The previous validation function didn't allow to create new users and modify linkname of existing ones. Additionally I created new doesLinkNameExist helper function.

"""
Django validation and HTML form handling.

TODO:
    Default value for field
    Field labels
    Nestable Forms
    FatalValidationError -- short-circuits all other validators on a form
    ValidationWarning
    "This form field requires foo.js" and form.js_includes()
"""

from util import ValidationError
from widgets import *
from fields import *
from forms import *
from models import *