Update libglew-dev for travis

Update libglew as well

.travis.yml

@@ -1,5 +1,5 @@
 language: cpp
-sudo: false
+sudo: required
 dist: trusty
 
 os:
@@ -39,8 +39,12 @@ before_install:
       export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01';
     fi;
   # Add coverall for C++ so coverall.io could be triggered. Even it should be --coverage and gcov.
+  # Install updated libglew-dev since the version provided by trusty is outdated
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
       pip install --user cpp-coveralls requests[security];
+      wget http://mirrors.kernel.org/ubuntu/pool/main/g/glew/libglew-dev_1.13.0-2_amd64.deb;
+      wget http://mirrors.kernel.org/ubuntu/pool/main/g/glew/libglew1.13_1.13.0-2_amd64.deb;
+      sudo dpkg -i libglew1.13_1.13.0-2_amd64.deb libglew-dev_1.13.0-2_amd64.deb;
     else
       brew update; brew update;
       brew install ccache glew wxwidgets llvm40;
@@ -69,7 +73,7 @@ addons:
       - libasound2-dev
       - libopenal-dev
       - freeglut3-dev
-      - libglew-dev
+      #- libglew-dev
       - libc6-dev
       - llvm-4.0
       - llvm-4.0-dev