The FeedsController#refresh method no longer returns a 404 if there are no unread entries in the feed after fetching it.

The reason that this is unnecessary is that entries are not actually returned to a GET /feeds/refresh call anymore. After the refresh AJAX call returns, a GET show call is immediately done, and this is the call that has to handle a possible 404 return.

fixes #169
Added regression test for the bug fixed in commit b320c0c84a726e9b938e333a8ad33fd52db7160f
The FeedsController#refresh method no longer passes the "entries" local to the rendered partial. It was no longer used.

Changed acceptance tests related to refreshing feeds, to account for the latest changes.