travis-ci add kubuntu-backports for newer cmake

-stop manually downloading cmake

.travis.yml

@@ -14,6 +14,7 @@ cache:
 addons:
   apt:
     sources:
+    - kubuntu-backports
     - llvm-toolchain-precise-3.5
     - ubuntu-toolchain-r-test
     packages:
@@ -33,9 +34,6 @@ addons:
     - texlive-extra-utils
 
 before_install:
-  - wget http://www.cmake.org/files/v3.2/cmake-3.2.1-Linux-x86_64.tar.gz
-  - tar zxf cmake-3.2.1-Linux-x86_64.tar.gz
-  - export PATH=`pwd`/cmake-3.2.1-Linux-x86_64/bin:$PATH
   - if [ "$CC" = "clang" ]; then export CC="clang-3.5" CXX="clang++-3.5"; fi
   - if [ "$CC" = "gcc" ]; then export CC="gcc-4.8" CXX="g++-4.8"; fi