3xx shouldn't be classified as errors in gadgets.io.makeRequest

This patch removes the classification of 3xx responses as errors (populating resp.errors) in gadgets.io.makeRequest.

To avoid incorrectly parsing 3xx response content (often HTML snippets), such responses are treated as TEXT.

[beaton, 2009-11-11 19:32:58]

I took a look, and the rest of SHINDIG-1180 looks reasonable.

Thanks for fixing this.

http://codereview.appspot.com/152070/diff/1/2
File features/src/main/javascript/features/core.io/io.js (right):

http://codereview.appspot.com/152070/diff/1/2#newcode170
features/src/main/javascript/features/core.io/io.js:170: params.CONTENT_TYPE =
"TEXT";
kind of hacky, but OK I think.

[Jon Weygandt, 2009-11-11 20:29:55]

Are there valid use cases where the 3xx status codes would be used by a gadget?
Does the default HttpFetcher follow redirects, or does it return and make the
gadget do the following?

Apart from the questions, the code looks fine.

[Jon Weygandt, 2009-11-11 20:54:14]

Is it clear from the OS specification that redirects should (or should not be)
followed?

Would this be something that we would want to add, along with perhaps a
parameter to turn it on/off?