Added travis file.

.travis.yml

+# Sample .travis.yml for R projects from https://github.com/craigcitro/r-travis
+
+language: c
+
+before_install:
+  - curl -OL http://raw.github.com/craigcitro/r-travis/master/scripts/travis-tool.sh
+  - chmod 755 ./travis-tool.sh
+  - ./travis-tool.sh bootstrap
+
+install:
+  - ./travis-tool.sh install_deps
+
+script: ./travis-tool.sh run_tests
+
+on_failure:
+  - ./travis-tool.sh dump_logs
+
+notifications:
+  email:
+    on_success: change
+    on_failure: change