Experimental support for django 1.7
Fix tests
Fix travis
fix for django v1.7: delete & access incorrect key
Add documentation
Code cleanup
Django 1.8 futureproof
cms helper file does not belong here
Added missing field from 1.7 migration
Fixed FK fields to work with Django 1.7 migrations

FilerFileField and FilerFolderField hard-coded the positional 'to' argument but Django migrations deconstruct for ForeignKey will pass this in via kwargs. Updated fields to use kwargs when hard-coding 'to' so migrations work.
Removed invalid kwarg before calling __init__

This was breaking since Field does not support the limit_choices_to argument
The line noise in file.py is just removing an unused variable 'other_widget'
Merge pull request #1 from jsma/feature/django-1.7

Added missing field from 1.7 migration
Merge pull request #447 from nephila/feature/django-1.7

Support for django 1.7