Added user email modification to admin page

Pressing the user settings button brings up a list of all jellyfin
users, and allows you to add or change their stored email addresses.
Additionally, changed emails.json to use user ID instead of username.
The program automatically converts the file to the new format at start.

jellyfin_accounts/jf_api.py

@@ -35,11 +35,21 @@ class Jellyfin:
            "User-Agent": self.useragent,
            "X-Emby-Authorization": self.auth
         }
-    def getUsers(self, username="all"):
-        response = requests.get(self.server+"/emby/Users/Public").json()
-        if username == "all":
-            return response
+    def getUsers(self, username="all", id="all", public=True):
+        if public:
+            response = requests.get(self.server+"/emby/Users/Public").json()
         else:
+            response = requests.get(self.server+"/emby/Users",
+                                    headers=self.header,
+                                    params={'Username': self.username,
+                                            'Pw': self.password})
+            if response.status_code == 200:
+                response = response.json()
+            else:
+                raise self.AuthenticationRequiredError
+        if username == "all" and id == "all":
+            return response
+        elif id == "all":
             match = False
             for user in response:
                 if user['Name'] == username:
@@ -47,6 +57,14 @@ class Jellyfin:
                     return user
             if not match:
                 raise self.UserNotFoundError
+        else:
+            match = False
+            for user in response:
+                if user['Id'] == id:
+                    match = True
+                    return user
+            if not match:
+                raise self.UserNotFoundError
     def authenticate(self, username, password):
         self.username = username
         self.password = password