Add cross browser support table

[taitems]

Add a table indicating which browser versions support window.onerror and online/offline events.

This can probably be sourced using spoon.net, and posted to caniuse.com when done.

[taitems]

Initial tests:

Note, you can help test by running appfail.reporting.runTests(); and checking your console.

Browser             ononline/onoffline      navigator.onLine    JSON        localStorage
----------------------------------------------------------------------------------------------------
IE7                 false                   true
IE8                 false                   true
IE9                 true                    true
Chrome 20           true                    true                true        true
Firefox 13          true                    true                true        true
Opera 11            false                   true                true        true
Safari 5.1.7        true                    true                true        true