Rename json_path_get to json_get
[DEV-127] Add json_set script function

- Also switch from spaces to tabs
[DEV-127] Add json_append operation.
[DEV-127] Add docs for json_set and json_append
[DEV-127] Combine 2 json objects with json_append
Improve int and real parsing.
Fix double decref in set
Fix pv issue with json_get
Add more docs.
Merge pull request #4 from flowroute/set

[DEV-127] Add json_set