fix(rxEnvironmentMatch): More correctly match environments

Previously `('unified-preprod' | rxEnvironmentMatch )` would return
`false` in the `preprod` environment, even though it was supposed to
return `true`. This was because of using `Environment.get().name` as
the basis for comparison.

We now use `Environment.envCheck` as the basis, which corrects this
problem.

Closes #595
Merge pull request #596 from rackerlabs/595_fix_rxEnvironmentMatch

fix(rxEnvironmentMatch): More correctly match environments