Misc. bug fixes from lgtm.com (2) (#9474)

* Remove dead branch of ternary: `gift` is always truthy here

Problem found here:

- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/server/libs/amazonPayments.js?sort=name&dir=ASC&mode=heatmap&excluded=false#x5a22f31110a55091:1

* Remove superfluous argument, preenUserHistory only takes two args

Problem found here:

- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/server/libs/cron.js?sort=name&dir=ASC&mode=heatmap&excluded=false#xf16a045ecabb07f6:1

* Cleanup: remove useless assignments

Problems found here:

- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/client/store/actions/shops.js?sort=name&dir=ASC&mode=heatmap&excluded=false#xf782ed2cf920441%3A1
- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/client/app.vue?sort=name&dir=ASC&mode=heatmap&excluded=false#x172c1dda85e84dc8%3A1
- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/client/components/settings/site.vue#x9b3afee802a3a8f8%3A1
- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/client/components/selectMembersModal.vue?sort=name&dir=ASC&mode=heatmap&excluded=false#x1fbc2a3d62facd70:1
- https://lgtm.com/projects/g/HabitRPG/habitrpg/snapshot/dist-98076885-1510577633582/files/website/common/script/libs/taskClasses.js?sort=name&dir=ASC&mode=heatmap&excluded=false#x41ce0e121a4defee:1

* Fix online editor whitespace change.

website/client/components/settings/site.vue

@@ -341,7 +341,6 @@ export default {
       await axios.put(`/api/v3/user/auth/update-${attribute}`, updates);
       alert(this.$t(`${attribute}Success`));
       this.user[attribute] = updates[attribute];
-      updates = {};
     },
     openRestoreModal () {
       this.$root.$emit('bv::show::modal', 'restore');