Specs should activate a metric and rescue failures

If we only check for enabled/activated, RailsBestPractices won't be
loaded, but if we 'activate' it, it will crash on Rubies that do
not have Ripper.

The solution is to attempt to activate it, and interpret an exception
as a failed activation
Skip SimpleCov functional test when running SimpleCov
Update RSpec expectation config
Capture warnings on test run

Borrowed from vcr

Run with rake spec
or see options for rake spec task in Rakefile
Specify pattern of files for RSpec to test
Add quality spec from vcr/bundler
Remove trailing whitespace
Centralize simplecov config