Fix LinterRegistry specs to not pollute actual registry
Fix LinterRegistry specs to not pollute actual registry

In the process of writing some other specs, there was a problem where
the linters inserted into the registry by this spec were breaking other
specs.

Fix by modifying the specs to not modify the global linter registry.

Change-Id: I22c0e282003da4f6ebc8f52758654f338e64bd5f
Reviewed-on: https://gerrit.causes.com/30918
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@causes.com>
Reviewed-by: Shane da Silva <6f6e68d1df92f30cb4b3ce35260ddf94a402f33d@causes.com>

artemartemov/scss-lint-hdm