[GA Module] Session/Localstorage not available breaking the entire site

[luigimannoni]

Prior to Safari 11 (iPads and iPhones with old iOS running) in private mode they restrict access to Local and Sessionstorage, this means each accessing these methods throws an error on Safari 10 and below and the website is unusable.

We detected some uncatched errors on these lines:
https://github.com/moreonion/campaignion/blob/7.x-1.x/campaignion_google_analytics/tracking.js#L493
https://github.com/moreonion/campaignion/blob/7.x-1.x/campaignion_google_analytics/tracking.js#L510

Potentially also the get methods are affected on that.