Update .travis.yml

.travis.yml

@@ -1 +1,26 @@
-script: make && make install
+compiler:
+  - gcc
+
+# the install step will take care of deploying a newer cmake version
+install:    
+  # first we create a directory for the CMake binaries
+  - DEPS_DIR="${TRAVIS_BUILD_DIR}/deps"
+  - mkdir ${DEPS_DIR} && cd ${DEPS_DIR}
+  # we use wget to fetch the cmake binaries
+  - travis_retry wget --no-check-certificate https://cmake.org/files/v3.3/cmake-3.3.2-Linux-x86_64.tar.gz
+  # this is optional, but useful:
+  # do a quick md5 check to ensure that the archive we downloaded did not get compromised
+  - echo "f3546812c11ce7f5d64dc132a566b749 *cmake-3.3.2-Linux-x86_64.tar.gz" > cmake_md5.txt
+  - md5sum -c cmake_md5.txt
+  # extract the binaries; the output here is quite lengthy,
+  # so we swallow it to not clutter up the travis console
+  - tar -xvf cmake-3.3.2-Linux-x86_64.tar.gz > /dev/null
+  - mv cmake-3.3.2-Linux-x86_64 cmake-install
+  # add both the top-level directory and the bin directory from the archive
+  # to the system PATH. By adding it to the front of the path we hide the
+  # preinstalled CMake with our own.
+  - PATH=${DEPS_DIR}/cmake-install:${DEPS_DIR}/cmake-install/bin:$PATH
+  # don't forget to switch back to the main build directory once you are done
+  - cd ${TRAVIS_BUILD_DIR}
+
+script: make && sudo make install