Simplify `__virtual__` logic.
Mocked test for `salt.modules.alternatives.display()`
Mocked test for `salt.modules.alternatives.show_current()`
Mocked test for `salt.modules.alternatives.check_installed()`
Mocked test for `salt.modules.alternatives.install()`
Mocked test for `salt.modules.alternatives.remove()`
Remove un-neded import.
Merge pull request #6347 from s0undt3ch/sprint/mock-salt.modules.alternatives

Mocked tests for `salt.modules.alternatives`