Update travis file

Author: hamishmack

.travis.yml

@@ -1,15 +1,33 @@
-language: haskell
+env:
+  - GHCVER=7.4.1
+  - GHCVER=7.4.2
+  - GHCVER=7.6.3
+  - GHCVER=7.8.3
+
 before_install:
+  - sudo add-apt-repository -y ppa:hvr/ghc
   - sudo apt-get update -qq
-  - sudo apt-get --no-install-recommends install libgtksourceview-3.0-dev alex happy
-  - cabal install Cabal
-  - cabal install cabal-install
-  - PATH="$HOME/.cabal/bin:$PATH" cabal install gtk2hs-buildtools
+  - sudo apt-get --no-install-recommends install libgtk2.0-dev libgtk-3-dev
+  - sudo apt-get install cabal-install-1.20 ghc-$GHCVER
+  - export PATH=$HOME/.cabal/bin:/opt/ghc/$GHCVER/bin:/opt/cabal/1.20/bin:$PATH
+  - cabal update
+  - |
+    if [ $GHCVER = "head" ] || [ ${GHCVER%.*} = "7.8" ]; then
+      sudo apt-get install happy-1.19.3 alex-3.1.3
+      export PATH=/opt/alex/3.1.3/bin:/opt/happy/1.19.3/bin:$PATH
+    else
+      sudo apt-get install happy alex
+    fi
+
 install:
-  - PATH="$HOME/.cabal/bin:$PATH" cabal install cabal-meta cabal-src
+  - cabal install Cabal
+  - cabal install gtk2hs-buildtools
+
 script:
-  - PATH="$HOME/.cabal/bin:$PATH" cabal-meta install --force-reinstalls
+  - cabal install
+
 notifications:
   irc:
     channels: "irc.freenode.net#leksah"
+    skip_join: true
   email: true