Fix: 0003822: basedir restriction on some servers

Any upload method apart from disk requires php tmp directory to be readable.
Use move_uploaded_file instead of Copy as move_uploaded_file appears to ignore_openbasedir restriction.
If temp file is not readable, we attempt to get filesize from post data instead

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@2873 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9