Add cmake install to travis build.

.travis.yml

@@ -16,6 +16,7 @@ compiler:
 script:
   - cmake -G "Unix Makefiles" -DASSIMP_ENABLE_BOOST_WORKAROUND=YES -DASSIMP_NO_EXPORT=$TRAVIS_NO_EXPORT -STATIC_BUILD=$TRAVIS_STATIC_BUILD
   - make
+  - sudo make install
   - cd test/unit
   - ../../bin/unit