[1.7.x] Fixed #22302 -- Updated Finnish locale formats

Backport of aaa21102592e96c543d60513755d6c81f639f122 from master.
[1.7.x] Improved strip_tags and clarified documentation

The fact that strip_tags cannot guarantee to really strip all
non-safe HTML content was not clear enough. Also see:
https://www.djangoproject.com/weblog/2014/mar/22/strip-tags-advisory/
Backport of 6ca6c36f82b from master.
[1.7.x] Added release note about strip_tags improvement

Backport of 1c8dbb0cc from master.
[1.7.x] Tweaked strip_tags tests to pass on Python 3.3

Backport of 6a0291bdaf from master.
[1.7.x] Fixed #22256 -- Replaced bad fallback for missing PATH

Thanks Baptiste Mispelon for the review.
Backport of acee46fc9 from master.
[1.7.x] Fixed #22241 -- Selectively added line breaks in admin read-only fields

When content is supposed to contain HTML, we do not try to add
line breaks in read-only contents.
Thanks Alexander Todorov for the report.
Backport of c94bff2 from master.
[1.7.x] Removed an unused variable.

Backport of 684e8a941b from master