Allow better customisation of app

[JAFpwrBI_001]

1. Need more flexibility when styling an app so it can be blended with the organisational branding. Current set up has very limited colour options and ability to add a logo.
2. Would like the option to remove the 'all' audience when a user has access to multiple audiences. We spend a lot of time making sure content is organised correctly to give users context, and the 'all' audience makes a bit of a mockery of that.