Need timeout parameter for image upload

[yasushinj]

IMS server has a tendency to hang in many different reasons, so image upload function needs a parameter to time out http post request.

Please add it to the upload method and pass it to http post method.

== current method signature ==
def upload_image(self, upload_host, filename, id_storage, id_project=None,
properties=None, sync=False, protocol=None):

As a note, I was adding a timeout parameter manually to http post request before when manual build was allowed. Now, due to the setup error reported in issue#57 does not allow manual build any longer.