Implement Card based UI

Created by: mray

Here are things that pop into my head in no particular order:

• package and use the font "Lato" #316 (closed)
• restructure footer as proposed in #739 (closed)
• restructure header as proposed in #739 (closed)
• use "material"-like theme as start
• make sure interface is "touch" - proof
• have a working responsive version
• apply color palette from design manual
• create javascript fall-back solution
• add card concept as proposed in #739 (closed)
• add on-off toggles with smooth transition and indicating installing process
• create enabled/ disabeled categories
• auto-sort cards inside categories (depending on having app-pages)
• define sensible categories for configuration cards, #1226 (closed) ?
• Store more app meta-information #832

Whenever possible adhere to the design manual