Imp travis run tests

This should allow the .travis.yml file to just run the single test on different DBs calling travis_run_tests for every module
Something like
```
travis_run_tests 7.0 account_invoice_production_lot $HOME/reporting-engine $HOME/stock-logistics-workflow $HOME/webkit-tools
travis_run_tests 7.0 picking_dispatch_wave $HOME/reporting-engine $HOME/stock-logistics-workflow $HOME/webkit-tools
```
Also see https://github.com/OCA/account-invoice-reporting/pull/4#issuecomment-48040090