Add support to JSON literals, and set array literal parsing behaviour

Besides arrays, you can create dictionaries and more complex structures using JSON syntax. For example: 

     staff = '{
        "boss": {
           "name": "John", 
           "age": 42 
        }, 
        "staff": [
           {
              "name": "Mark" 
              "age": 35 
           }, 
           {
              "name": "Bill" 
              "age": 44 
           } 
        ] 
     } '

**NOTE**: Remember to wrap the JSON strings in single quotes for a correct analysis