variable "index" should be "counter"

fix https://github.com/lesspass/lesspass/issues/178

src/lesspass.js

@@ -36,7 +36,7 @@ var defaultPasswordProfile = {
   keylen: 32,
   digest: 'sha256',
   length: 16,
-  index: 1,
+  counter: 1,
   iterations: 100000
 };
 

tests/v2/api.tests.js

@@ -74,6 +74,15 @@ describe('LessPass v2', function() {
         assert.equal("sB>{qF}wN%/-fm", generatedPassword);
       });
     });
+    it('render password with default options', function() {
+      this.timeout(10000);
+      var site = 'example.org';
+      var login = 'contact@example.org';
+      var masterPassword = 'password';
+      return LessPass.generatePassword(site, login, masterPassword).then(function(generatedPassword) {
+        assert.equal('WHLpUL)e00[iHR+w', generatedPassword);
+      });
+    });
   });
 });