Add initial localStorage support for intermittent offline beacons

[Ryan Sorensen (rcs)]

This adds support for queuing request into localStorage when they can't be loaded immediately.

The queue will try to fire all requests off to the collector whenever a request is requested and successful.

I haven't been able to test in a browser without localStorage support -- any tips there?

[Ryan Sorensen (rcs)]

#23

[Alexander Dean (alexanderdean)]

Ryan Sorensen (@rcs) - whoah, this is awesome! Thanks for this. Two things:

1. Confusingly, hasLocalStorage does not indicate whether JavaScript can access that localStorage. So you will get errors in some Firefoxes as per JavaScript tracker fails on Firefox with "Always ask" setting for cookies snowplow#163 Suggestion: add a new method to helpers.js which is localStorageAccessible and return false in the catch {} block (where hasLocalStorage returns true)
2. Have you signed our CLA yet? https://github.com/snowplow/snowplow/wiki/CLA

[Ryan Sorensen (rcs)]

Grabbed the code out of Modernizr, since it's explicitly dealing with some private browsing features that wouldn't be hit otherwise.

The CLA was submitted yesterday.

[Alexander Dean (alexanderdean)]

Thanks Ryan Sorensen (@rcs) - code and CLA looks great. Will merge this into a branch for a 0.13.0 release... Will need quite a lot of testing at our end to check it doesn't break anything...

[Alexander Dean (alexanderdean)]

This has been pulled into master through the 1.0.0 work - big thanks Ryan Sorensen (@rcs) ! Closing.

[Alexander Dean (alexanderdean)]

My bad - this is going into 2.0.0, reopening till then...

[Alexander Dean (alexanderdean)]

This is published now - huge thanks, Ryan Sorensen (@rcs), closing