Merge pull request #117 from simphony/speed-up-build

speed-up builds

.travis.yml

@@ -1,7 +1,12 @@
 language: python
 python:
   - "2.7"
-
+
+cache:
+  pip: true
+  directories:
+  - $HOME/.ccache
+
 env:
   - SIMPHONY_VERSION=master
 matrix:
@@ -10,8 +15,11 @@ matrix:
 
 before_install:
   - sudo apt-get update -qq
-  - sudo apt-get install mpi-default-bin mpi-default-dev
-
+  - sudo apt-get install mpi-default-bin mpi-default-dev ccache
+  - sudo ln -s ccache /usr/local/bin/mpic++
+  - export PATH=/usr/lib/ccache:${PATH}
+  - ccache -s
+
 install:
   # build and install lammps
   - ./install_external.sh
@@ -27,6 +35,7 @@ script:
   - coverage run -m unittest discover
   - python setup.py build_sphinx
   - cd examples/dem_billiards/; python dem_billiards.py
+  - cd ..
 
 after_success:
   - pip install codecov