Install MPI for CI

.gitlab-ci.yml

-Python 2.7 POCL:
+Python 2.7 POCL MPI:
   script:
   - export PY_EXE=python2.7
   - export PYOPENCL_TEST=portable
-  - export EXTRA_INSTALL="numpy mako"
+  - export EXTRA_INSTALL="numpy mako mpi4py"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
   - ". ./build-and-test-py-project.sh"
   tags:
   - python2.7
   - pocl
+  - mpi
+  except:
+  - tags
+
+Python 3.5 POCL MPI:
+  script:
+  - export PY_EXE=python3.5
+  - export PYOPENCL_TEST=portable
+  - export EXTRA_INSTALL="numpy mako mpi4py"
+  - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
+  - ". ./build-and-test-py-project.sh"
+  tags:
+  - python3.5
+  - pocl
+  - mpi
   except:
   - tags