cgal 4.4 is too old, now it gets updated on travis

Former-commit-id: c33a0984c249be3e42d3aa2678b24db5c8e6721c

.appveyor.yml

@@ -13,7 +13,7 @@ build_script:
   - cd c:\projects\libigl\tutorial
   - mkdir build
   - cd build
-  - cmake -G "Visual Studio 14 2015 Win64"
+  - cmake -G "Visual Studio 14 2015 Win64" ../
   - set MSBuildLogger="C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
   - set MSBuildOptions=/v:m /p:Configuration=Release /logger:%MSBuildLogger%
   - msbuild %MSBuildOptions% libigl_tutorials.sln

.travis.yml

@@ -36,7 +36,7 @@ matrix:
       script:
         - brew update
         - brew upgrade cmake
-        - brew install cgal
+        - brew upgrade cgal
         - git submodule update --init --recursive
         - cd tutorial
         - mkdir build