Fixed #15789 -- Set the decimal precisio to avoid an exception in the...

Fixed #15789 -- Set the decimal precisio to avoid an exception in the floatformat filter, and added a few more tests. Thanks akaihola for the report, igalarzab for the patch and ptone for the review.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@17297 bcc190cf-cafb-0310-a4f2-bffc1f526a37