Add some linting rules for the CI (#587)

* enable one-var rule

* enable indent rule

* enable no-multiple-empty-lines rule

* enable no-empty rule

* enable no-trailing-spaces rule

* enable no-extra-semi rule

* add eslint rules to fix block spacing

* enable max-statements-per-line rule

* enable brace-style rule

* fix some spacing issues and add future rules

* add code suggestions

src/components/itemcontextmenu.js

@@ -52,8 +52,6 @@ define(["apphost", "globalize", "connectionManager", "itemHelper", "appRouter",
             //}
         }
 
-
-
         if (item.IsFolder || item.Type === "MusicArtist" || item.Type === "MusicGenre") {
             if (item.CollectionType !== "livetv") {
                 if (options.shuffle !== false) {