[backend] Check file existance, use underscores in camera unique name (#33)

* Add more comments and logging, fix configManager barf, add underscores

* apply spotless

* Add more verbose logging

* Update VisionSourceManager.java

photon-server/src/main/java/org/photonvision/server/Main.java

@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2020 Photon Vision.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package org.photonvision.server;
-
-public class Main {
-
-    public static void main(String[] args) {
-        Server.main(5800);
-    }
-}