add release tests

(fix minor stuff found by release tets)

xt/release/changes.t

@@ -0,0 +1,27 @@
+use strict;
+use warnings;
+use Test::More;
+BEGIN { 
+  plan skip_all => 'test requires Test::CPAN::Changes' 
+    unless eval q{ use Test::CPAN::Changes; 1 };
+};
+use Test::CPAN::Changes;
+use FindBin;
+use File::Spec;
+
+chdir(File::Spec->catdir($FindBin::Bin, File::Spec->updir, File::Spec->updir));
+
+do {
+  my $old = \&Test::Builder::carp;
+  my $new = sub {
+    my($self, @messages) = @_;
+    return if $messages[0] =~ /^Date ".*" is not in the recommend format/;
+    $old->($self, @messages);
+  };
+  no warnings 'redefine';
+  *Test::Builder::carp = $new;
+};
+
+changes_file_ok;
+
+done_testing;