Extract translatable strings from edx.utils.validate.js.

The JS validation utility functions from edx.utils.validate.js file
that are used on the combined login registration page include some
translatable strings that weren't getting extracted by the i18n tools
because they were defined inside underscore template strings.

This commit pulls the translatable strings out of the templates
to make sure gettext detects the strings at extraction time.

common/static/common/js/utils/edx.utils.validate.js

@@ -24,12 +24,13 @@
             var _fn = {
                 validate: {
 
+                   template: _.template( '<li><%= content %></li>' ),
+
                     msg: {
-                        email: '<li><%- gettext("The email address you\'ve provided isn\'t formatted correctly.") %></li>',
-                        min: '<li><%- _.sprintf( gettext("%(field)s must have at least %(count)d characters."), context ) %></li>',
-                        max: '<li><%- _.sprintf( gettext("%(field)s can only contain up to %(count)d characters."), context ) %></li>',
-                        required: '<li><%- _.sprintf( gettext("Please enter your %(field)s."), context ) %></li>',
-                        custom: '<li><%= content %></li>'
+                        email: gettext("The email address you've provided isn't formatted correctly."),
+                        min: gettext("%(field)s must have at least %(count)d characters."),
+                        max: gettext("%(field)s can only contain up to %(count)d characters."),
+                        required: gettext("Please enter your %(field)s.")
                     },
 
                     field: function( el ) {
@@ -131,9 +132,9 @@
 
                     getMessage: function( $el, tests ) {
                         var txt = [],
-                            tpl,
                             label,
-                            obj,
+                            context,
+                            content,
                             customMsg;
 
                         _.each( tests, function( value, key ) {
@@ -143,30 +144,20 @@
 
                                 // If the field has a custom error msg attached, use it
                                 if ( customMsg ) {
-                                    tpl = _fn.validate.msg.custom;
-
-                                    obj = {
-                                        content: customMsg
-                                    };
+                                    content = customMsg;
                                 } else {
-                                    tpl = _fn.validate.msg[key];
-
-                                    obj = {
-                                        // We pass the context object to the template so that
-                                        // we can perform variable interpolation using sprintf
-                                        context: {
-                                            field: label
-                                        }
-                                    };
+                                    context = {field: label};
 
                                     if ( key === 'min' ) {
-                                        obj.context.count = parseInt( $el.attr('minlength'), 10 );
+                                        context.count = parseInt( $el.attr('minlength'), 10 );
                                     } else if ( key === 'max' ) {
-                                        obj.context.count = parseInt( $el.attr('maxlength'), 10 );
+                                        context.count = parseInt( $el.attr('maxlength'), 10 );
                                     }
+
+                                    content = _.sprintf( _fn.validate.msg[key], context );
                                 }
 
-                                txt.push( _.template( tpl, obj ) );
+                                txt.push( _fn.validate.template( {content: content} ) );
                             }
                         });