Fix OS X travis failure (#186)

Author: Keno

.travis.yml

@@ -15,5 +15,8 @@ env:
 before_install:
   - sh ./conf/travis-install-mpi.sh $MPI_IMPL
   - export PATH=$HOME/OpenMPI/bin:$PATH
+# Work around OpenMPI attempting to create overly long temporary
+# file names - and erroring as a result
+  - export TMPDIR=/tmp
 after_success:
   - if [ "$TRAVIS_JULIA_VERSION" = nightly ]; then julia -e 'cd(Pkg.dir("MPI")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(Coveralls.process_folder()); Codecov.submit(Coveralls.process_folder())'; fi

conf/travis-install-mpi.sh

@@ -12,7 +12,6 @@ case "$os" in
     Darwin)
         brew update
         brew upgrade cmake
-	    brew upgrade gcc
         case "$MPI_IMPL" in
             mpich|mpich3)
                 brew install mpich