Various password logic fixes on client and server-side

Fixes #6399
Fixes #6400

test/user.js

@@ -71,7 +71,7 @@ describe('User', function () {
 
 		it('should error with invalid password', function (done) {
 			User.create({ username: 'test', password: '1' }, function (err) {
-				assert.equal(err.message, '[[user:change_password_error_length]]');
+				assert.equal(err.message, '[[reset_password:password_too_short]]');
 				done();
 			});
 		});