Override DDT data decorator

Add main.smoke to sample properties file
Add tests for robottelo.data decorator
Refactor all ddt.data decorator imports to robottelo.data
Organize alphabetically imports for some modules

To run smoke tests just change the main.smoke config to 1 in robottelo.properties file.

When not running smoke tests (main.smoke config is 0) then:

```shell
$ nosetests --collect-only -q tests/foreman
----------------------------------------------------------------------
Ran 2417 tests in 0.086s

OK
```

When running smoke tests (main.smoke config is 1) then:

```shell
$ nosetests --collect-only -q tests/foreman
----------------------------------------------------------------------
Ran 921 tests in 0.033s

OK
```

Related to #731