Release v0.35: Premium accounts

Enhancements:

• Add support for premium accounts & make private projects a premium feature. Free users can only create public projects, while premium users can choose between public and private when creating the project.
• Improve the notification icon by replacing the old world icon with a bell icon. This should help more clearly identify it as a notification icon. (#318)
• Improve placement of profile actions: Demote the edit profile button from floating action button to flat button. Add a button to create a new project as the primary action on the profile page. This should help solve the confusion of users who think they can create a project by clicking the button that actually takes them to the edit profile page (#292)

Fixes:

• Do not show file diffs when plain text between two document version is the same (#240)