fix for utf16 decoding error + exposing values through the Registry class

The edited code within RegistryParse.py will need to be double checked. I was running it over a registry hive that had one value where the raw byte data was missing an 0x00 at the end, resulting in a unicode truncated string error. I wasn't able to identify any instances where the previous code block was actually making any difference to the raw data, so thought it best to replace the entire block. I've tested it on a number of registry hives (Windows 7) that have all worked out.