Improve response and dispatch event in AuthenticationFailureHandler

[EmmanuelVella]

Response status code is changed from 401 (Unauthorized) to 400 (Bad Request) (see http://stackoverflow.com/a/1960453). I think this makes more sense if the login parameters are invalid.

Response is now a valid json object containing a code and a message attributes.

The handler now dispatch a failure event.

[carlcraig]

The updated Json Response is good, although i am unsure if 400 is the appropriate response code. I would normally consider 400 a result of malformed request. i.e. missing parameters or data etc.

I think if the username/password is incorrect it should return a 401.
If the username or password parameter is missing, should return 400.
What do you think?

The failure event will be useful too.

[EmmanuelVella]

Yeah I'm not 100% sure about the 400 status code in this case, so I think we can keep the old 401 (PR is updated).

[slashfan]

401 is the proper code to use in my opinion. But nice work !
I'm waiting for travis to finish the build. Is it ok to merge for you ?

[EmmanuelVella]

Travis build passed, you can merge it if @carlcraig is ok ;)

[carlcraig]

👍 Looks Good