This imports the JSON support for Qt 5 from
playground/qtbinaryjson.
It adds a fast, fully compliant json parser, a
convenient C++ API, conversion to and from
QVariants and a binary format for JSON that is
extremely fast to use together with the C++ API.
Change-Id: If9e3a21a4241d388d0abaa446b6824f9cc6edb1c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>