Onboarding process should provide explanations for permissions

[jwise]

The very first thing that a user sees when they launch Cobble right now is a permission request for calendar (not the end of the world if they deny), then a request for location (absolutely the end of the world if they deny). The traditional approach is 'ask to ask' (i.e., do not display the system dialog until we think they will click yes) -- and, perhaps, ask during the pairing process (with an explanation). We should take the traditional approach.

[matejdro]

Designs are there (See #91). Someone just needs to implement them :)