set travis back to gcc 4.6 version

The gcc-4.8 patch requires travis to download and install gcc-4.8
from an ubuntu ppa. This takes a few mintues and the gcc build is
already fairly close to the timelimit, so this change can push
some builds over the edge. Since it doesn't seem to be strictly
necessary right now, I comment out the code for v 4.8 install.

.travis.yml

@@ -14,11 +14,11 @@ matrix:
       env: WML_TESTS=true STRICT_COMPILATION=True
     - compiler: gcc
       env: WML_TESTS=true STRICT_COMPILATION=False
-before_install:
-    - if [ "$CXX" = "g++" ]; then sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y; fi
-    - if [ "$CXX" = "g++" ]; then sudo apt-get update -qq; fi
-    - if [ "$CXX" = "g++" ]; then sudo apt-get install g++-4.8; fi
-    - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8"; fi
+#before_install:  # Commented this block out because the download can take a few minutes and cause the gcc build to timeout.
+#    - if [ "$CXX" = "g++" ]; then sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y; fi
+#    - if [ "$CXX" = "g++" ]; then sudo apt-get update -qq; fi
+#    - if [ "$CXX" = "g++" ]; then sudo apt-get install g++-4.8; fi
+#    - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8"; fi
 install:
     - sudo apt-get update -qq
     - sudo apt-get install -qq libboost-iostreams-dev libboost-program-options-dev libboost-regex-dev libboost-system-dev libboost-test-dev libcairo2-dev libfribidi-dev libpango1.0-dev libsdl-image1.2-dev libsdl-mixer1.2-dev libsdl-net1.2-dev libsdl-ttf2.0-dev