Add Integration Tests with Oracle Database Express Edition on Travis CI

[qwazer]

Add Integration Tests with Oracle Database Express Edition on Travis CI

Use this
https://github.com/cbandy/travis-oracle
and
travis-ci/travis-ci#689
sequelize/sequelize#4261
as starting points

[qwazer]

https://github.com/qwazer/scheme2ddl/releases/tag/v2.4.0