wrapped json.loads with a try block, and checking for 403 errors

When CloudSearch was returning a 403 error due to access control settings, boto was raising the following Exception:

    JSONDecodeError at /app/meet2/search/
    Expecting value: line 1 column 1 (char 0)

which was coming from:

    boto/cloudsearch/search.py line 292
    data = json.loads(r.content)

I wrapped the loads call with a try block, and added code to detect the 403 error and raise a SearchServiceException with the Amazon error message inside