feat: allow tokens in localize, localize progress bar time (#4060)

It allows you to use string as an key for the language files but have a default value that's different. In this case, we have a key of progress bar timing: currentTime={1} duration={2} which is used so that we have a descriptive key to what is happening. The default value matches that default value in en.json: {1} of {2}. The reason for the default value is so that the translation uses {1} of {2} for the actual localization without requiring en.json to be included in videojs by default.

Fix #4024.

build/grunt.js

@@ -145,6 +145,10 @@ module.exports = function(grunt) {
         files: ['src/css/**/*'],
         tasks: ['skin']
       },
+      lang: {
+        files: ['lang/**/*.json'],
+        tasks: ['vjslanguages']
+      }
     },
     connect: {
       dev: {
@@ -408,6 +412,7 @@ module.exports = function(grunt) {
         'browserify:watchnovtt',
         'browserify:tests',
         'watch:skin',
+        'watch:lang',
         'watch:dist'
       ],
       // Run multiple watch tasks in parallel