fix mongo setObject if key/value is empty string

test/database/hash.js

@@ -42,6 +42,17 @@ describe('Hash methods', function () {
 				});
 			});
 		});
+
+		it('should not error if a key is empty string', function (done) {
+			db.setObject('emptyField', {'': '', b: 1}, function (err) {
+				assert.ifError(err);
+				db.getObject('emptyField', function (err, data) {
+					assert.ifError(err);
+					console.log(data);
+					done();
+				});
+			});
+		});
 	});
 
 	describe('setObjectField()', function () {