Revert "new file:   .travis.yml"

This reverts commit 818bcfd48548bb3aca607cf4d125b9ff8db1e625.
Revert "Revert "new file:   .travis.yml""

This reverts commit 95648e47109adf0198c2553b8673399e3d98b2fc.
Revert "modified:   src/test/java/demo/rpn/RpnCalculatorShould.java"

This reverts commit 7ec23686102eb6b5ecc1176fd342d6e6a92c617b.