Simple Server Backend

[nathanlesage]

This needs to still be discussed and properly scoped, but there has been the suggestion of implementing a small server. What it should do is:

• Be entirely optional. The core aim of Conferia is to be as simple to use without much technical knowledge, and hosting a server is certainly not one of them. So all functionality provided by the server must be optional.
• Allow user-account creation for cloud-saving the personal schedule. This way, users can switch devices and keep their schedule with them without the need for cumbersome import/export mechanisms.