Add stacks/:id/settings page, update settings

Fixes #13
Roll back stack changes on transition away from settings page
Merge pull request #19 from bantic/stack-settings-page-13

Add stacks/:id/settings page, update settings
Introduce a flow for creating a user. Add error handling.
Move adapters to adapters, add api and auth
Merge pull request #18 from mixonic/create-account

Introduce a flow for creating a user. Add error handling.