Update cmake for travis-ci

.travis.yml

@@ -24,6 +24,8 @@ before_install:
     - if [[ -d $HOME/docker ]]; then ls $HOME/docker/*.tar.gz | xargs -I {file} sh -c "zcat {file} | docker load"; fi
 addons:
     apt:
+        sources:
+            - george-edison55-precise-backports # cmake 3.2.3 / doxygen 1.8.3
         packages:
             - autoconf
             - autotools-dev
@@ -31,6 +33,8 @@ addons:
             - libev-dev
             - asciidoc
             - xmlto
+            - cmake
+            - cmake-data
 script:
     - ./autogen.sh
     - ./configure && make