The JSON generator and JSON parser being used in ESP RainMaker were
taken from third party repos. In order to ensure that they are
better in sync with the upstream repos, they have now been included
as submodules.
Please run `git submodule update --init --recursive` once to pull in
these submodules.
Eg. Add a pre-generated JSON object, say {"name":"val"} into another object, giving
a result {"pregen":{"name":"val"}}
Similarly allow to read entire object string during parsing.
