Updated and made changes necessary for the new version of rapidjson.
Looks good on ubuntu under the compilers I can test with, needs MSVC testing.
We had some internal changes to rapidjson but these didn't seem necessary with
the new version. Haven't done any performance testing, initial estimates put it at
nearly the same speed for json serialization. Could probably optimize things.
relates #82, #121
longs should now properly serialize under 32 or 64 bit machines.
long long, unsigned long long, and long double now serialize as base10
strings instead of base64.
see issue #72
