Update json-parser to new version

We have new release of json-parser. In this commit I took latest
git-version of it.

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
Fix sources to build with new json-parser

Since one of commit [0] API has changed.

[0] https://github.com/udp/json-parser/commit/83fd76873cf1125f2c8fc4627a452bf9bee4a7b0

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>