CBQE-0: fix ViewCreateTask.execute hangs when 404

[2013-05-13 03:25:17,540] - [rest_client:687] ERROR - http://10.1.4.24:8091//couchBase/default/_design/upgrade-test-view0 error 404 reason: status: 404, content: Not found. Not found.
Exception in thread Cluster_Thread:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "lib/tasks/taskmanager.py", line 31, in run
    task.step(self)
  File "lib/tasks/task.py", line 54, in step
    self.execute(task_manager)
  File "lib/tasks/task.py", line 1137, in execute
    content, meta = self.rest.get_ddoc(self.bucket, self.design_doc_name)
  File "lib/membase/api/rest_client.py", line 457, in get_ddoc
    status, json, meta = self._get_design_doc(bucket, ddoc_name)
  File "lib/membase/api/rest_client.py", line 578, in _get_design_doc
    json_parsed = json.loads(content)
  File "/usr/lib/python2.7/json/__init__.py", line 326, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 384, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

Change-Id: I5962570828db9594f1e949098967cb6455ea2bfe
Reviewed-on: http://review.couchbase.org/26263
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>