Use coverage kit to enforce maximum coverage and bump coverage

ruby_core_extensions.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.3"
   spec.add_development_dependency "rake"
   spec.add_development_dependency 'rspec'
-  spec.add_development_dependency 'simplecov'
+  spec.add_development_dependency 'coverage-kit'
   spec.add_development_dependency 'simplecov-rcov'
   spec.add_development_dependency 'coveralls'
   spec.add_development_dependency 'travis'

spec/support/coverage.rb

@@ -1,29 +1,4 @@
-MINIMUM_COVERAGE = 87
-
-unless ENV['COVERAGE'] == 'off'
-  require 'simplecov'
-  require 'simplecov-rcov'
-  require 'coveralls'
-  Coveralls.wear!
-
-  SimpleCov.formatters = [
-    SimpleCov::Formatter::RcovFormatter,
-    Coveralls::SimpleCov::Formatter
-  ]
-  SimpleCov.start do
-    add_filter '/vendor/'
-    add_filter '/spec/'
-    add_filter '/lib/error_handling/'
-    add_group 'lib', 'lib'
-  end
-  SimpleCov.at_exit do
-    SimpleCov.result.format!
-    percent = SimpleCov.result.covered_percent
-    unless percent >= MINIMUM_COVERAGE
-      puts '*' * 80
-      puts "Coverage must be above #{MINIMUM_COVERAGE}%. It is #{format('%.2f', percent)}%"
-      puts '*' * 80
-      Kernel.exit(1)
-    end
-  end
-end
+require 'simplecov-rcov'
+require 'coveralls'
+require 'coverage/kit'
+Coverage::Kit.setup(minimum_coverage: 87.2)