Convert and delete some old API tests

Remove the following modules:

1. `test_computeresource`
2. `test_configtemplate`
3. `test_domain`
4. `test_environments`

The first three contained no working tests and no interesting test stubs. The
existing test stubs were for goals such as creating or deleting an entity. Given
that all four relevant entities are already tested in module
`test_multiple_paths`, there is no value to the stubs.

The fourth module contains tests for creating environments with valid and
invalid names. Port these tests to module `test_environment_v2`.

Remove outdated module references from the API documentation.
As far as I can tell, yes. If you attempt to create an environment whose name contains non-alphanumeric characters or whitespace, an error message is returned. The error message is:

> Name is alphanumeric and cannot contain space

So the API is definitely asking for a limited set of characters. This is not limited to the API, either. According to [this bug](https://bugzilla.redhat.com/show_bug.cgi?id=1126033), the web UI also restricts users to the same set of characters.

I received an indeterminate response when asking about this on `#satellite6`. Ah - I suppose I should keep on copy-pasting a question on this matter into IRC.