ui: update ui elements with new ui classes / components

[zven]

@umut0 did some great work with centralizing and optimizing our commonly used ui elements https://github.com/mint-o-badges/badgr-ui/issues/306

Neverthelesse, we still need to include those in our pages.

[umut0]

What needs to be done:

Go through components and:

• remove all references to the old css-classes
• use newly created OEB-Elements
• use the predefined paddings and margins
• create new OEB-Elements when needed and if nothing else exists yet
• check if new Layout works with existing component

Components to be checked:

• [x] Startpage
• [x] Login Page
• [x] Desktop Navigation
• [ ] Mobile Nav
• [x] Award Badge (reworked without extra fields)
• [x] Bulk award feature (reworked except File Upload field)
• [x] Backpack
• [x] Badge Detail Pages
• [x] Issuer Registration
• [x] Badge Catalog
• [x] reset-password page
• [ ] signup-page
• [ ] Badge-edit page
• [ ] Badge-bulk-award page
• [ ] Issuer-edit page
• [ ] issuer-create-staff dialog

Components still missing:

• [x] Dialog
• [ ] FileUpload
• [ ] Notifications
• [x] Tabs
• [x] Select
• [x] Icons
• [ ] Dropdown
• [ ] Radio Group
• [x] Collapsible