[lua-library] json parser: from string to table

This function build a table recursively from a json string passed by the
lua source. In the json table:
- json objects are lua tables;
- json arrays are lua arrays (first index is 1);
- numbers, strings and booleans are the same;
[lua-library] oauth serialize url

Just like the oauth api, three parameters:
1-) number of strings to serialize;
2-) start index to serialize;
3-) strings to serialize;

The strings are a lua table where its key is the url parameter and the
table value is this parameter value;