use container-based infrastructure

.travis.yml

@@ -1,36 +1,35 @@
 language: cpp
 
+sudo: false
+
 env:
   matrix:
     - COMPILER=g++-4.9
-      COMPILER_PACKAGE=g++-4.9
-
     - COMPILER=g++-4.8
-      COMPILER_PACKAGE=g++-4.8
-
     - COMPILER=g++-4.7
-      COMPILER_PACKAGE=g++-4.7
-
     - COMPILER=clang++-3.5
-      COMPILER_PACKAGE=clang-3.5
-
     - COMPILER=clang++-3.6
-      COMPILER_PACKAGE=clang-3.6
 
-before_install:
- - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
- - sudo add-apt-repository ppa:boost-latest/ppa -y
- - sudo add-apt-repository ppa:h-rayflood/llvm-upper -y
- - sudo apt-get update -qq
- - sudo apt-get install -qq libboost1.54-dev libboost-regex1.54-dev libboost-program-options1.54-dev build-essential ${COMPILER_PACKAGE}
- - ${COMPILER} --version
- - wget http://www.cmake.org/files/v3.2/cmake-3.2.2.tar.gz
- - tar xf cmake-3.2.2.tar.gz
- - cd cmake-3.2.2
- - ./configure
- - make
- - sudo make install
- - cd ..
+addons:
+  apt:
+    sources:
+     - ubuntu-toolchain-r-test
+     - boost-latest
+     - llvm-toolchain-precise-3.5
+     - llvm-toolchain-precise-3.6
+     - llvm-toolchain-precise-3.7
+     - george-edison55-precise-backports
+    packages:
+     - g++-4.7
+     - g++-4.8
+     - g++-4.9
+     - clang-3.5
+     - clang-3.6
+     - build-essential
+     - cmake
+     - libboost1.55-dev
+     - libboost-regex1.55-dev
+     - libboost-program-options1.55-dev
 
 before_script:
  - export CXX=${COMPILER}