[travis] try to use containers base infrastructure

.travis.yml

@@ -1,3 +1,5 @@
+sudo: false
+
 env:
  - CABALVER=1.16 GHCVER=7.0.4
  - CABALVER=1.16 GHCVER=7.4.2
@@ -10,10 +12,22 @@ matrix:
   allow_failures:
    - env: CABALVER=head GHCVER=head
 
+addons:
+    apt:
+        sources:
+         - hvr-ghc
+        packages:
+         - cabal-install-1.18
+         - cabal-install-1.20
+         - cabal-install-1.22
+         - ghc-7.0.4
+         - ghc-7.4.2
+         - ghc-7.6.3
+         - ghc-7.8.4
+         - ghc-7.10.1
+         - ghc-head
+
 before_install:
- - travis_retry sudo add-apt-repository -y ppa:hvr/ghc
- - travis_retry sudo apt-get update
- - travis_retry sudo apt-get install cabal-install-$CABALVER ghc-$GHCVER # see note about happy/alex
  - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
 
 install: