[PWA] Service worker app cache duration

@brodriguezs can’t answer if it happens or not. generally speaking, sometimes it may still takes time to update the pages but I’ve the feeling that generally speaking it’s better with workbox than sw-toolbox

with workbox you will generate and deploy a list of hash of your bundled js, so if you use lazy loading it will contains x.js entries identified with hash. if you do a modification, then only the hash of the related js will be updated. this list helps workbox to notice which files have to be updated

...
{
    "url": "build/31.js",
   "revision": "c46081f51218522127856c4cba816d56"
},
{
   "url": "build/32.js",
   "revision": "5c6c59dfcbc226bef6d56afc4f07502e"
}
...

note: if you use Ionic v4, don’t go for workbox, go for the integrated Angular v6 pwa support, faster to add to the build