Update AJAX operations to call the ajaxErrorHandler if the operation
doesn't succeed.

Fixes https://www.pivotaltracker.com/story/show/61753458
reload the current page after updating datastream content (instead of displaying the content)
Merge pull request #177 from futures/http-api-fixes

Improving error handling to HTML UI.  Fixes https://github.com/futures/fcrepo4/pull/177