Server comm failure callbacks

[joescii]

In this PR I added front-end hooks for applications to be notified of possible server communication problems. There are 4 new public methods on lift:

lift.addAjaxOnCommFailure()
lift.addAjaxOnCommSuccess()
lift.addCometOnCommFailure()
lift.addCometOnCommSuccess()

With these in place, it is possible for an app to show the user that server communication has potentially been lost after some threshold number of failure events for instance.

See relevant ML thread.

[joescii]

Ah, travis failure. Looks like I've been too loose with teh JavaScriptz

[joescii]

Any ideas why we're failing to boot in the travis script? I wouldn't have expected a JS enhancement to cause that... :-/

[eltimn]

"src/main/resources/toserve/lift.js: line 110, col 24, Possible strict violation"

It looks like it doesn't like the use of this on line 110. This SO article explains it.

If we just assign the function to a variable var notifyAll = function instead of function notifyAll then the error goes away. I'm not sure if that's the best solution or not, but, I updated your branch locally with that change. I'll push that now.

[joescii]

Awesome, thanks for the help Tim. I guess I missed the second jshint complaint when I saw the fail to boot stacktrace.

We could make that function call less fancy now. When I first started it, I thought I wouldn't know the number of parameters. Now that it's worked out, we know it's either 1 or 2 args.

[joescii]

Nullifying this PR per @Shadowfiend's recognition that any Lift user can already accomplish the same effect by configuring settings.ajaxPost and settings.ajaxGet to be notified of failure or success of ajax and comet communication respectively.