General cleanup: fix some bugs, some refactoring (#65)

* Merged mod file upload in version creation, mod creation and
  version file add to one function;  This makes sure that they are
  consistent
* Made some fields on `User` optional: `github_id`, `avatar_url`, `bio`.
    * We may not want to publicly show the `github_id` to everyone
      with access to the API
    * If we allow non-github users, some of those fields would be
      invalid; some oauth providers may not have avatars or bios
* Made CORS origins should configurable
* Made `--reconfigure-indices` and `--reset-indices` exit after
  completion instead of starting the server

src/models/teams.rs

@@ -2,7 +2,6 @@ use super::ids::Base62Id;
 use crate::models::users::UserId;
 use serde::{Deserialize, Serialize};
 
-//TODO Implement Item for teams
 /// The ID of a team
 #[derive(Copy, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(from = "Base62Id")]
@@ -26,6 +25,6 @@ pub struct TeamMember {
     pub user_id: UserId,
     /// The name of the user
     pub name: String,
-    ///The role of the use in the team
+    /// The role of the user in the team
     pub role: String,
 }