Moved vendored js/css into public/vendor and documented sources (#1484) (#2241)

* Cleaning up public/ and documenting js/css libs.

This commit mostly addresses #1484 by moving vendor'ed plugins into a
vendor/ directory and documenting their upstream source and license in
vendor/librejs.html.

This also proves gitea is using only open source js/css libraries which
helps toward reaching #1524.

* Removing unused css file.

The version of this file in use is located at:
  vendor/plugins/highlight/github.css

* Cleaned up librejs.html and added javascript header

A SafeJS function was added to templates/helper.go to allow keeping
comments inside of javascript.

A javascript comment was added in the header of templates/base/head.tmpl
to mark all non-inline source as free.

The librejs.html file was updated to meet the current librejs spec. I
have now verified that the librejs plugin detects most of the scripts
included in gitea and suspect the non-free detections are the result of
a bug in the plugin. I believe this commit is enough to meet the C0.0
requirement of #1534.

* Updating SafeJS function per lint suggestion

* Added VERSIONS file, per request

public/vendor/plugins/codemirror/mode/vue/vue.js

@@ -0,0 +1,69 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function (mod) {
+  "use strict";
+  if (typeof exports === "object" && typeof module === "object") {// CommonJS
+    mod(require("../../lib/codemirror"),
+        require("../../addon/mode/overlay"),
+        require("../xml/xml"),
+        require("../javascript/javascript"),
+        require("../coffeescript/coffeescript"),
+        require("../css/css"),
+        require("../sass/sass"),
+        require("../stylus/stylus"),
+        require("../jade/jade"),
+        require("../handlebars/handlebars"));
+  } else if (typeof define === "function" && define.amd) { // AMD
+    define(["../../lib/codemirror",
+            "../../addon/mode/overlay",
+            "../xml/xml",
+            "../javascript/javascript",
+            "../coffeescript/coffeescript",
+            "../css/css",
+            "../sass/sass",
+            "../stylus/stylus",
+            "../jade/jade",
+            "../handlebars/handlebars"], mod);
+  } else { // Plain browser env
+    mod(CodeMirror);
+  }
+})(function (CodeMirror) {
+  var tagLanguages = {
+    script: [
+      ["lang", /coffee(script)?/, "coffeescript"],
+      ["type", /^(?:text|application)\/(?:x-)?coffee(?:script)?$/, "coffeescript"]
+    ],
+    style: [
+      ["lang", /^stylus$/i, "stylus"],
+      ["lang", /^sass$/i, "sass"],
+      ["type", /^(text\/)?(x-)?styl(us)?$/i, "stylus"],
+      ["type", /^text\/sass/i, "sass"]
+    ],
+    template: [
+      ["lang", /^vue-template$/i, "vue"],
+      ["lang", /^jade$/i, "jade"],
+      ["lang", /^handlebars$/i, "handlebars"],
+      ["type", /^(text\/)?(x-)?jade$/i, "jade"],
+      ["type", /^text\/x-handlebars-template$/i, "handlebars"],
+      [null, null, "vue-template"]
+    ]
+  };
+
+  CodeMirror.defineMode("vue-template", function (config, parserConfig) {
+    var mustacheOverlay = {
+      token: function (stream) {
+        if (stream.match(/^\{\{.*?\}\}/)) return "meta mustache";
+        while (stream.next() && !stream.match("{{", false)) {}
+        return null;
+      }
+    };
+    return CodeMirror.overlayMode(CodeMirror.getMode(config, parserConfig.backdrop || "text/html"), mustacheOverlay);
+  });
+
+  CodeMirror.defineMode("vue", function (config) {
+    return CodeMirror.getMode(config, {name: "htmlmixed", tags: tagLanguages});
+  }, "htmlmixed", "xml", "javascript", "coffeescript", "css", "sass", "stylus", "jade", "handlebars");
+
+  CodeMirror.defineMIME("script/x-vue", "vue");
+});