Subscriptions client-side

[slaweet]

• [x] setup GoPay
• [x] specify subscription plans
• [x] display subscriptions in user profile
• [x] dislpay subscription plans
• [x] popup offering subscription
• [x] subscribe workflow for logged in user
• [x] subscribe workflow for anonymous user
• [x] disable access to /practice/relations/, redirect /practice/ to /practice/images for not subscribed users
• [x] add subscribed flag to subscriptionService
• [x] reload page on login
• [x] handle 100% discount code
• [x] deploy to production with hidden menu item
• [x] update relations data from znackuj.anatom.cz
• [x] set active subscription on production for testing
• [x] critical bugs reported by Marek in spreasheet (fix typeahead filtering)

[papousek]

Sample data for subscriptions: https://github.com/adaptive-learning/proso-apps/blob/master/testproject/test_data/subscription/plans.json

Command to load data for subscriptions: ./manage.py load_subscription_plans