Added feature to dump payload of files using manage.py dumpdata
Merge branch 'develop' of https://github.com/stefanfoulis/django-filer into serialize-payload
Merge branch 'develop' into serialize-payload

Conflicts:
	filer/fields/multistorage_file.py
Rebased PR#382 from rollstudio to the latest develop branch, b240633
Added extra hint for importing dumped data
Merge pull request #383 from jrief/serialize-payload

Rebased PR#382 'Fixed loaddata raising IOError' from rollstudio