Added Adder

Added Adder, an Internet-based, free and open source electronic voting system which employs strong cryptography.

See: http://web.archive.org/web/20110908060059/http://cryptodrm.engr.uconn.edu/adder/
and http://www.dagstuhl.de/Materials/Files/07/07311/07311.KiayiasAggelos.Paper.pdf