Improve test coverage

[fchatterji]

What github issue is this PR for, if any?

Resolves https://github.com/doubleunion/arooo/issues/453 What does this code do, and why?

added some specs for comments controller added specs to the admin controller removed duplicated simplecov config in rails bin improved simplecov config in spec helper to add coverage groups (models, controllers...) How is this code tested? Are any database migrations required by this change?

no Are there any configuration or environment changes needed?

no Screenshots please :)

[fchatterji]

@compwron sorry had to close the previous PR and open this one (the other one was created from my main branch by mistake)