Make tests pass on both RSpec 2 and 3

lib/mutant/rspec/killer.rb

@@ -32,7 +32,7 @@ module Mutant
           return false
         end
 
-        reporter = RSpec::Core::Reporter.new
+        reporter = RSpec.configuration.reporter
 
         example_groups.each do |group|
           return true unless group.run(reporter)

spec/unit/mutant/cli_new_spec.rb

@@ -13,9 +13,9 @@ end
 shared_examples_for 'a cli parser' do
   subject { cli.config }
 
-  its(:strategy) { should eql(expected_strategy) }
-  its(:reporter) { should eql(expected_reporter) }
-  its(:matcher)  { should eql(expected_matcher)  }
+  it { expect(subject.strategy).to eql(expected_strategy) }
+  it { expect(subject.reporter).to eql(expected_reporter) }
+  it { expect(subject.matcher).to  eql(expected_matcher)  }
 end
 
 describe Mutant::CLI, '.new' do

spec/unit/mutant/rspec/killer_spec.rb

@@ -42,7 +42,7 @@ describe Mutant::Rspec::Killer, '.new' do
   context 'when run exits zero' do
     let(:exit_status) { 0 }
 
-    its(:killed?) { should be(false) }
+    it { expect(subject.killed?).to be(false) }
 
     it { should be_a(described_class) }
   end
@@ -50,7 +50,7 @@ describe Mutant::Rspec::Killer, '.new' do
   context 'when run exits nonzero' do
     let(:exit_status) { 1 }
 
-    its(:killed?) { should be(true) }
+    it { expect(subject.killed?).to be(true) }
 
     it { should be_a(described_class) }
   end