repo: update repository description field to contain more than 256 symbols (#5219)

* Update repository description field to contain more than 256 symbols

- update repository model - description field now is `TEXT` and limited by 4000 symbols
- new migration
- add description to html forms - repo creation and repo settings
- add translation for description

* Update for description field, new features

- add autosize (height) for description textarea, new plugin
- set max description length to 512 symbols
- update locales

* Fix migration - typo in var

* Update repo description behaviour

- add textarea autosize for /repo/create
- add symbols counter under description testarea (create/edit)

* Fix function definition - it a var

* Revert ru-RU locale

* Update by review

- Use type `varchar(512)` in migration
- Remove unused files from autosize plugin

* Fix migration - new project paths

* Fixes after review 2

- copyright year
- format includes
- use switch instead of multi-if

* Remove unused `default:` option.

public/js/gogs.js

@@ -1443,3 +1443,24 @@ $(function () {
     if ($('.user.signin').length > 0) return;
     $('form').areYouSure();
 });
+
+function showMessageMaxLength(maxLen, textElemId, counterId) {
+    var $msg = $('#'+textElemId);                      //text message
+    $('#'+counterId).html(maxLen - $msg.val().length); //symbols count
+
+    var onMessageKey = function (e) {
+        var $msg = $(this);
+        var text = $msg.val();
+        var len = text.length;
+        var remainder = maxLen - len;
+
+        if (len >= maxLen) {
+            $msg.val($msg.val().substr(0, maxLen));
+            remainder = 0;
+        }
+
+        $('#'+counterId).html(remainder);
+    };
+
+    $msg.keyup(onMessageKey).keydown(onMessageKey);
+}