Merge pull request #666 from libgit2/arthur/ruby-two-point-four

Fix deprecation warning when running tests with Ruby 2.4.0

Author: arthurschreiber

test/lib_test.rb

@@ -14,7 +14,7 @@ def test_libgit2_version
     version = Rugged::libgit2_version
     assert_equal version.length, 3
     version.each do |i|
-      assert i.is_a? Fixnum
+      assert i.is_a? Integer
     end
   end