Update Xcode

.travis.yml

@@ -2,12 +2,15 @@ language: cpp
 compiler: g++
 
 matrix:
+  allow_failures:
+    - os: osx
+      osx_image: xcode8.2
   include:
     - os: linux
       dist: trusty
       sudo: required
     - os: osx
-      osx_image: xcode7.2
+      osx_image: xcode8.2
 
 before_install:
   - if [[ "$TRAVIS_OS_NAME" != "osx" ]]; then sudo apt-get -qq update ; fi