Create a permission system to limit account privileges

[retrixe]

There should be a way to set permissions for each account. I'm not sure how this will work yet.

Permission ideas:

• Ability to manage other people's accounts.
• Ability to change one's own password.
• Ability to access a server's status.
• Ability to perform specific actions on the server (this would just be console access, statistics access and files access).
• Maybe even more granular permissions for per-folder access? This will need a lot of thinking for a good permission design.

[retrixe]

#13 adds the "actions" syntax to define particular actions users can do, for the purpose of fine-grained configuration of the new logging feature. These can be reused for permissions, however, they are not nearly as fine-grained as we would like.

#13 (comment) is an idea to address this by adding "generics" of sorts to the syntax. We should implement this or try another solution when adding this feature to octyne.

[retrixe]

We will need to migrate users.json to a new format (ideally, this file shouldn't be modified by end users anymore, and removed from documentation entirely, since we provide account management endpoints).

We will want to have the concept of roles with permissions that can be applied to users.