Clean up indentation, line lengths
Added class attribute for translation class

This makes it easier to work with translations.  I had done this already
for other translated models but not for Organization and Project.
Clean up spacing/indentation
Form class for translated models

This is a first pass at a form class that handles the translated fields
as if they were all on the same model instead of spread out between two
models.

I added some helper methods to the TranslatedModel class to make it easier
to implement this.

CreateOrganizationForm is an example of using TranslatedModelForm.

This functionality is needed as part of #458 and #463, but when fully
implemented and tested could help refactor a lot of the translation code.
Skeleton for organization creation view

Begins to implement #458
Base form class for translated models

This should have been added as part of 65fb039cfa5ebb248729644275d77a02de26b5ba
Template for organization creation view

This should have been added in 37fe41e292e23ab93fec98464a9423203f29333a
Tests for create organization view

These test basic access control and object creation functionality of the
views.
Add members field to organization form

Add a members field to OrganizationModelForm to allow users to specify
users that should be associated with the organization when they are
creating the organization.

In order to implement this, I created a custom field, UserEmailField that
converts a comma-separated list of user emails to a queryset of User
objects.
Added image asset creation for Organizations

Images can be uploaded to set the featured asset of the newly created
organization.  I had to add a custom form to support compressing the file
or URL field down to a single value.
Support image URLs for Organizations
Added type to membership relation

I updated the through class for the members field of the Organization and
Project models so it includes a type field that differentiates between
owners of the Organization and Project and members.  These will eventually
have different permissions.
Set the owner to the current user

Set the owner member of the Organization to the current user when creating
an Organization
Add "pending" status

For PublishedModel, add a "pending" choice to the status field for items
that need approval by an admin.  This will eventually be used in the
creation flow for Projects/Organizations.
Add publication status fields

Add the publication status field (via the PublishedModel base class) to
the Organization and Project models.  Also add a contact info field to
the Organization model.
Fix errors related to updated through model

There were some errors breaking tests (and a similar issue I found in the
admin) related to using User.organizations.add() and User.projects.add().

These things no longer work with after adding the custom through model in
499a0c8c00683c539d7f6d070e144082bcdafdcf.  Instead, I needed to construct
the through model explicitly.
Set status to 'pending' when user creates orgs
Publish existing projects and organizations

After schema migration 0017_add_publication_status_and_contact_info, the
newly added status field is set to the default of 'draft'.  Since we
previously didn't have any publication status control on these models, we
assume that we want them to be published.  This data migration sets the
status of all Organizations and Projects to 'published'.
Only show published projects and organizations

In contexts where projects and organizations are listed, only show published
projects and organizations.
Factored sending mail to admins into a function

Moved some of the logic in the post_save signal handler for
SiteContactMessage into a utility function, storybase_user.utils.send_admin_mail.
I renamed to signal handler to send_message_to_admins to make its purpose
seem less general.