Try another kind of travis build

.travis.yml

@@ -1,4 +1,3 @@
-sudo: required
 language: cpp
 
 before_install:    
@@ -6,8 +5,7 @@ before_install:
     - export CXXFLAGS="$CXXFLAGS -DTRAVIS"
 
 install:
-    - sudo apt-get install -qq libwxgtk3.0-dev libwxgtk3.0-0 libssh2-1-dev
-    - if [ "$CXX" = "g++" ]; then sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 98; fi
+    - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8"; fi
 
 # Build with both gcc and clang
 compiler:
@@ -19,6 +17,9 @@ addons:
         sources:
         - ubuntu-toolchain-r-test
         packages:
+        - libwxgtk3.0-dev
+        - libwxgtk3.0-0
+        - libssh2-1-dev
         - gcc-4.8
         - g++-4.8
         - clang