Some error checking put in. When a new network is created and the

Some error checking put in. When a new network is created and the
connection fails, an alert message is displayed, and connection
attempts cease.  Retrying with a correct barcode works.  Not perfect
yet, but in my testing I have found this version much better than the
previous setup: at least errors are detected and the user is informed.

git-svn-id: http://zxing.googlecode.com/svn/trunk@1470 59b500cc-1b3d-0410-9834-0bbf25fbcc57