Unblocking CLI tests for content-host command.

The two Bugzilla issues that were blocking all of our CLI tests for the
content-host command, namely BZs #1099655 and #1084722, have been
verified, so I have removed the ``bzbug`` decorators and ran the
tests (smoke=1).

```bash
$ nosetests -c robottelo.properties tests/foreman/cli/test_contenthost.py

Ran 6 tests in 244.344s

OK
```