GUI-1347 fixed bucket level paste, added timeout error handlers in bucket_contents javascript

fixed bucket level paste, added timeout error handlers in bucket_contents javascript

https://eucalyptus.atlassian.net/browse/GUI-1347
@dkavanagh : Most S3 errors seem to return a 400 status code instead of a 403, so we should probably handle both here.  See buckets.js for an example.