Merge pull request #87 from cdunn2001/master

2to3 (but only the changes which should work with python2 also)
fix gcc warning when CXXFLAGS contains '-Wextra'

json_value.cpp:179:26: warning: enumeral and non-enumeral type in conditional expression [enabled by default]

https://github.com/open-source-parsers/jsoncpp/pull/84