form.label_suffix colon on admin checkboxes

[Collin Anderson]

django1.5: ​http://snag.gy/JyMxI.jpg
django1.6b1: ​http://snag.gy/ilUNM.jpg

This is regression was introduced by #18134 584bd14dcfdee9585fec7794d53ce120ea73d0bc.

Here is the admin's algorithm for deciding when to add the colon:
​https://github.com/django/django/blob/master/django/contrib/admin/helpers.py#L126
After the admin sets up the label it wants, it calls field.label_tag which then adds the colon back.

[Tim Graham]

Adding a proposal to add an include_label_suffix kwarg to label_tag. Will update the docs if this looks reasonable.

[Tim Graham]

Added a more general solution that allows overriding label_suffix at the field level.

[Claude Paroz]

The patch is rather good, but I'm afraid it doesn't cover the use case when you call label_tag in a template to render a checkbox field:

{{ form.cb_field }} {{ form.cb_field.label_tag }}

No better solution to propose yet...

[Collin Anderson]

...another case where calling methods with arguments would be quite nice...

[Tim Graham]

We could recommend writing a custom filter for that case.

[Tim Graham <timograham@…>]

In 8676318d2dae9a570d2314e4e6da8c00aaf2e2a0:

Fixed #20805 -- Removed an extra colon beside checkboxes in the admin.

Thanks CollinAnderson for the report.

[Tim Graham <timograham@…>]

In dbbd2b1272e5a3ce7ab4b39b9a74f4ea725b104f:

[1.6.x] Fixed #20805 -- Removed an extra colon beside checkboxes in the admin.

Thanks CollinAnderson for the report.

Backport of 8676318d2d from master