travis: enable APT caching and make tests more verbose

Author: torbjoernk

.travis.yml

@@ -1,6 +1,8 @@
 language:
   - cpp
 
+cache: apt
+
 # why does Travis not allow for multi-dimensional build matrices?!?
 #  -> https://github.com/travis-ci/travis-ci/issues/1519
 env:
@@ -45,5 +47,5 @@ script:
   - cd build
   - cmake -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} -Dpfasst_WITH_MPI=${WITH_MPI} -Dpfasst_DISABLE_LIBCXX=ON -Dpfasst_BUILD_TESTS=ON -Dpfasst_BUILD_EXAMPLES=ON ..
   - make
-  - make test
+  - make test ARGS="-V"
   - make run_example_all