Remove leftover ref_extractor_spec file

Apparently it didn't get removed after the rename to ExtractsPath.

spec/lib/ref_extractor_spec.rb

-require 'spec_helper'
-
-describe ExtractsPath do
-  include ExtractsPath
-
-  let(:project) { double('project') }
-
-  before do
-    @project = project
-    project.stub(:branches).and_return(['master', 'foo/bar/baz'])
-    project.stub(:tags).and_return(['v1.0.0', 'v2.0.0'])
-  end
-
-  describe '#extract_ref' do
-    it "returns an empty pair when no @project is set" do
-      @project = nil
-      extract_ref('master/CHANGELOG').should == ['', '']
-    end
-
-    context "without a path" do
-      it "extracts a valid branch" do
-        extract_ref('master').should == ['master', '']
-      end
-
-      it "extracts a valid tag" do
-        extract_ref('v2.0.0').should == ['v2.0.0', '']
-      end
-
-      it "extracts a valid commit ref without a path" do
-        extract_ref('f4b14494ef6abf3d144c28e4af0c20143383e062').should ==
-          ['f4b14494ef6abf3d144c28e4af0c20143383e062', '']
-      end
-
-      it "falls back to a primitive split for an invalid ref" do
-        extract_ref('stable').should == ['stable', '']
-      end
-    end
-
-    context "with a path" do
-      it "extracts a valid branch" do
-        extract_ref('foo/bar/baz/CHANGELOG').should == ['foo/bar/baz', 'CHANGELOG']
-      end
-
-      it "extracts a valid tag" do
-        extract_ref('v2.0.0/CHANGELOG').should == ['v2.0.0', 'CHANGELOG']
-      end
-
-      it "extracts a valid commit SHA" do
-        extract_ref('f4b14494ef6abf3d144c28e4af0c20143383e062/CHANGELOG').should ==
-          ['f4b14494ef6abf3d144c28e4af0c20143383e062', 'CHANGELOG']
-      end
-
-      it "falls back to a primitive split for an invalid ref" do
-        extract_ref('stable/CHANGELOG').should == ['stable', 'CHANGELOG']
-      end
-    end
-  end
-end