The function of exporting PDF file in "All Grades" page doesn't support non-latin characters.
If the Grade Item or username contains non-latin characters, the characters will be skipped.
This patch add non-latin character support to this function, and use a property 'pdf.default.font' to set the font.
Actually, this is a pdf font issue, which also affect functions use FOP to produce PDF files. Some information can be found in SAK-21908
I use the property 'pdf.default.font' since it is used by
The version of iText is updated from 2.0.7 to 2.1.7 to support auto scan system fonts. iText 2.1.7 will scan folders including '/usr/share/fonts' while iText 2.0.7 only scan '/usr/share/fonts/default/TrueType'. So iText 2.1.7 can work much better in Linux envirnment.