Make theme able to load custom javascript (#1211)

* Make theme able to load custom javascript
- Look for the field 'customScript' in editorTheme (settings.js)
- Add it to mustach context
- Load list on template side (index.mst)

* Add unit tests for customScripts

* Code review edits : generic behavior for theme.page.[css|scripts]
- Use the same way to share css and javascript files from a theme
- Allow string instead of array for theme.page.scripts
- Remove old customScript field

test/red/api/theme_spec.js

@@ -55,7 +55,8 @@ describe("theme handler", function() {
                 page: {
                     title: "Test Page Title",
                     favicon: "/absolute/path/to/theme/icon",
-                    css: "/absolute/path/to/custom/css/file"
+                    css: "/absolute/path/to/custom/css/file",
+                    scripts: "/absolute/path/to/script.js"
                 },
                 header: {
                     title: "Test Header Title",
@@ -68,6 +69,10 @@ describe("theme handler", function() {
                     icon: "/absolute/path/to/deploy/button/image" // or null to remove image
                 },
 
+                customScripts: [
+                    "/absolute/path/to/script.js"
+                ],
+
                 menu: { // Hide unwanted menu items by id. see editor/js/main.js:loadEditor for complete list
                     "menu-item-import-library": false,
                     "menu-item-export-library": false,
@@ -93,6 +98,8 @@ describe("theme handler", function() {
         context.page.should.have.a.property("title","Test Page Title");
         context.should.have.a.property("header");
         context.header.should.have.a.property("title","Test Header Title");
+        context.page.should.have.a.property("css");
+        context.page.should.have.a.property("scripts");
 
         var settings = theme.settings();
         settings.should.have.a.property("deployButton");