Notifications management page

Mockups are here: https://invis.io/3POVGBKAQD8#/384778029_Parame-tres_-_Notif

Edit by @christophehenry:

This issue is quite macro. This is how I would break it down:

• add a NotificationsSettings model in djangoldp-notifications (startinblox/djangoldp-packages/djangoldp-notifications#18)
• expose user's parameters through HTTP API (/users/:user-id/parameters, maybe?) (startinblox/djangoldp-packages/djangoldp-notifications#19)
• add a user's parameter route on the front (#281 (closed))
• front page design (#281 (closed))
• add code to adjust notifications according to settings (startinblox/djangoldp-packages/djangoldp-notifications#17)

That is everything, I reckon? Should the UserParameter model only store notification configuration or be shared with other possible settings?