Unicode method on model should return unicode

The example of a __unicode__ model method should return a unicode value
instead of a string.
Fixed #22384 -- Deprecated reversing URLs by dotted path.
Merge pull request #2756 from tubaman/return_unicode

Unicode method on model should return unicode
Removed erroneous trailing comma in OLMapWidget.js.
Updated current state of MySQL Connector/Python.
Added a patch review checklist.
Fixed #22681 -- Made TarArchive recognize leading directories properly.
Fixed #22717 -- Auto-corrected missing ending slash in FileSystemStorage

Thanks David Fischer for the report and Moayad Mardini for the
review.
Fixed #22684 -- Amended SelectDateWidget.empty_label to accept a tuple of values.

Thanks danielsamuels for the report
Fixed #13776 -- Fixed ModelForm.is_valid() exception with non-nullable FK and blank=True.

Thanks peterbe for the report.
Fixed #10811 -- Assigning unsaved objects to FK, O2O and GFK raises ValueError.