Merge pull request #375 from SabreCat/develop

December backgrounds
feat(plans): add consecutive-month benefits for subscribers
feat(plans): add time traveler - buy individual mystery items
feat(plans): time traveler - by full sets
Merge pull request #376 from HabitRPG/block-subs

Block Subscriptions
fix(): remove some logs
i18n(plans): update wording cc @Alys
fix(plans): mystery 3014 promo
fix(plans): possible safe-check of gemcapextra cc @Sabrecat
fix(plans): move plan reset up for people in inn
fix(plans): fix conversion cap
fix(style): Prettify Market Gem