Document passing arguments with equal signs. Refs a1ba178d.

Add additional documentation regarding arguments passing with equal signs for which salt tries hard to turn into keyword arguments. The problem now arises because non supported arguments immediately thrown an exception.
Merge pull request #8384 from s0undt3ch/develop

Don't let Salt fail because `libcloud` is not installed.
Add the missing salt-cloud man page.
`doc/man/salt-cloud.7` is no longer generated.
Merge pull request #8387 from s0undt3ch/hotfix/salt-cloud-man

Add the missing salt-cloud man page.
Pass a relative path for proper test execution.

If we're trying to test a failure which happens when the path is not absolute, let's not pass it an absolute path in the first place.
The argument name is `arg`, not `args`.
Only delete the file if it actually exists.
Merge pull request #8388 from s0undt3ch/hotfix/test-file-remove

Pass a relative path for proper test execution.
Merge pull request #8385 from s0undt3ch/hotfix/test-kwarg

Document passing arguments with equal signs. Refs a1ba178d.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.
Deprecate `env` usage in favor of `saltenv`.