API keys support, bug fixes, improvements

app/manage.py

@@ -0,0 +1,45 @@
+import argparse
+from app.api_keys import Database
+
+def manage():
+    parser = argparse.ArgumentParser(description='LibreTranslate Manage Tools')
+    subparsers = parser.add_subparsers(help='', dest='command', required=True, title="Command List")
+
+    keys_parser = subparsers.add_parser('keys', help='Manage API keys database')
+    keys_subparser = keys_parser.add_subparsers(help='', dest='sub_command', title="Command List")
+
+    keys_add_parser = keys_subparser.add_parser('add', help='Add API keys to database')
+    keys_add_parser.add_argument('req_limit',
+                    type=int,
+                    help='Request Limits (per second)')
+    keys_add_parser.add_argument('--key',
+                    type=str,
+                    default="auto",
+                    required=False,
+                    help='API Key')
+
+    keys_remove_parser = keys_subparser.add_parser('remove', help='Remove API keys to database')
+    keys_remove_parser.add_argument('key',
+                    type=str,
+                    help='API Key')
+
+    args = parser.parse_args()
+    
+    if args.command == 'keys':
+        db = Database()
+        if args.sub_command is None:
+            # Print keys
+            keys = db.all()
+            if not keys:
+                print("There are no API keys")
+            else:
+                for item in keys:
+                    print("%s: %s" % item)
+
+        elif args.sub_command == 'add':
+            print(db.add(args.req_limit, args.key)[0])
+        elif args.sub_command == 'remove':
+            print(db.remove(args.key))
+    else:
+        parser.print_help()
+        exit(1)