Update .travis.yml

- Travis-ci now supports testing multiple ghc versions out of the box.
- Don't bother running the tests in tree and go straight to testing from
  the tarball realease

.travis.yml

@@ -1,33 +1,25 @@
-env:
+language: haskell
-  - GHCVER=7.4.2
+ghc:
-  - GHCVER=7.6.3
+  - 7.4
-  - GHCVER=7.8.2
+  - 7.6
-
+  - 7.8
-before_install:
-  - sudo add-apt-repository -y ppa:hvr/ghc
-  - sudo apt-get update
-  - sudo apt-get install cabal-install-1.18 ghc-$GHCVER happy-1.19.3
-  - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/1.18/bin:/opt/happy/1.19.3/bin:$PATH
 
 install:
   - cabal update
-  - cabal install --only-dependencies --enable-tests
+  - cabal install happy
+  - happy --version
+  - cabal install -j --only-dependencies --enable-tests
 
 script:
+  - cabal check
+  - cabal sdist
+  - export SRC_TGZ="$PWD/dist/$(cabal info . | awk '{print $2 ".tar.gz";exit}')"
+  - rm -rf /tmp/test && mkdir -p /tmp/test
+  - cd /tmp/test
+  - tar -xf $SRC_TGZ && cd ghc-mod*/
   - cabal configure --enable-tests
   - cabal build
   - cabal test
-  - cabal check
-  - cabal sdist
-  # The following scriptlet checks that the resulting source distribution can be built & installed
-  - export SRC_TGZ=$(cabal info . | awk '{print $2 ".tar.gz";exit}');
-    cd dist/;
-    if [ -f "$SRC_TGZ" ]; then
-      cabal install --enable-tests "$SRC_TGZ";
-    else
-      echo "expected '$SRC_TGZ' not found";
-      exit 1;
-    fi
 
 matrix:
   allow_failures: