[FIX] fn.showError: If message has an empty responseText then the whole object (usually a jqxhr object) was being passed through to the rest of the function which expects a string.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@47815 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] tracker files: Progress property is loaded, not position (also check for lengthComputable too - thanks Nelson)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@47816 b456876b-0849-0410-b77d-98878d47e9d5