Activate discounts on /pricing

Background: We currently have a discount route that activates a discount on users/me. Marketing would like this same route to be updated to /pricing so that the discount is activated on that page instead.

Scenario: Make [www.powr.io/ad_discount&code=[CODE](https://www.powr.io/pricing?ad_discount&code=[CODE)] redirect to www.powr.io/pricing instead of www.powr.io/users/me

Given that a route already exists for [www.powr.io/ad_discount&code=[CODE](http://www.powr.io/pricing?ad_discount&code=[CODE)]

When a user clicks on the URL

Then the URL will redirect to www.powr.io/pricing

Scenario: Create a user notification when a discount is activated on [www.powr.io/ad_discount&code=[CODE](http://www.powr.io/pricing?ad_discount&code=[CODE)]

Given that a discount is being offered and redirects to [www.powr.io/ad_discount&code=[CODE](http://www.powr.io/pricing?ad_discount&code=[CODE)]

When a user clicks on the above URL

Then a user notification should be created

Scenario: Link user notification and pro subscriptions

Given a user has activated a discount using [www.powr.io/ad_discount&code=[CODE](http://www.powr.io/pricing?ad_discount&code=[CODE)]

When a user notification is created and the discount is used

Then it should be linked to the corresponding pro subscription

Scenario: User is not logged in

Given a user is not logged in

When they click on [www.powr.io/ad_discount&code=[CODE](http://www.powr.io/pricing?ad_discount&code=[CODE)]

Then they should see a login in screen

And when they login they should be redirected to /pricing with the discount activated