Implemented "django-json-rpc" for fetching resource & its metadata.

As per the requirement for creating API to fetch the resources with its metadata, we have decided to go ahead with "**django-json-rpc**" ,  anyone can make use this API to get the resources information in their project, which are uploaded in all our metastudio platforms 

**Feature Enhancement**

* Implemented basic API for getting the resources and its metadata using browser url as well as from calling a method through shell

* ```__init__.py```  --> two urls added for json-rpc method, one for graphical json-rpc browser and web console and other is with the included ServiceProxy (which is "Proxy to test your JSON Service")

* ```settings.py```  --> Included 'jsonrpc' in INSTALLED_APPS in settings.

* ```rpc_resources.py```  --> json rpc method  "resources()"  implemented in this view file. Wil use this method in more generic way as and when required.

* Follow the steps for testing this implementation:
    *  **Install django-json-rpc**: 

         * go till **/manage.py** directory and do :  **pip install -r ../requirements.txt** 
         This will install ```django-json-rpc``` package of version 0.6.2

    *  **Now two ways of testing**
       * First of all run project ```python manage.py runserver```
       * Now open another tab and go to shell ```python manage.py shell``` and run following commands:

          --> from jsonrpc.proxy import ServiceProxy
          --> s = ServiceProxy('http://localhost:8000/json/')
          --> s.resources()
          
          This will return all public resources along with its metadata as a value in json format.

        * Second way is from browser url for graphical json-rpc browser and web console
           -->  Hit this url in browser ```http://127.0.0.1:8000/json/browse/```  
           This will open the "JSON-RPC Browser", in which you can see the method which is being called which is listed in methods section. when you click on that method "resources()" , it will show you the related information of this jsonrpc , such as "signature", "argument", "returns","idempotent",....and so on

           --> Call the method in that console as :  **jsonrpc.resources()**
             Which will show you the requesting json as : 
             {"id":"jsonrpc", "params":[], "method":"resources", "jsonrpc":"1.0"}
             and returned response (as Got -->) of all resources with its metadata in json format.
        
NOTE: run **python manage.py sync_existing_documents**