fix: get correct plural when n is in string

ref rubenv#313 fix rubenv#305

Author: zhuangya

src/catalog.js

@@ -258,6 +258,7 @@ angular.module('gettext').factory('gettextCatalog', function (gettextPlurals, ge
          * @description Translate a plural string with the given context.
          */
         getPlural: function (n, string, stringPlural, scope, context) {
+            n = typeof n === 'number' ? n : parseInt(n, 10);
             var fallbackLanguage = gettextFallbackLanguage(this.currentLanguage);
             string = this.getStringFormFor(this.currentLanguage, string, n, context) ||
                      this.getStringFormFor(fallbackLanguage, string, n, context) ||

test/unit/catalog.js

@@ -69,10 +69,18 @@ describe("Catalog", function () {
         assert.equal(catalog.getPlural(1, "Bird", "Birds"), "Bird");
     });
 
+    it("Should return singular when n is 1 in string", function () {
+        assert.equal(catalog.getPlural("1", "Bird", "Birds"), "Bird");
+    });
+
     it("Should return plural for unknown plural strings", function () {
         assert.equal(catalog.getPlural(2, "Bird", "Birds"), "Birds");
     });
 
+    it("Should return plural when n is more than 1 in string", function () {
+        assert.equal(catalog.getPlural("2", "Bird", "Birds"), "Birds");
+    });
+
     it("Should return singular for singular strings", function () {
         catalog.setCurrentLanguage("nl");
         catalog.setStrings("nl", {