[1.0.X] Fixed #6948 -- The join filter was escaping the literal value

that was passed in for the connector. This was contrary to what the
documentation for autoescaping said and to what every other filter does
with literal strings as arguments.

This is backwards incompatible for the situation of the literal string
containing one of the five special HTML characters: if you were writing
{{ foo|join:"&" }}, you now have to write {{ foo| join:"&" }}.
Previous behaviour was, as noted, a bug and contrary to what was
documented and expected.

Backport of r9442 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9443 bcc190cf-cafb-0310-a4f2-bffc1f526a37