Skip site-wide hooks when running git commit

`git commit --no-verify` exists since at least GIT 0.99.9m aka 1.0rc5

Issue reported in:
- http://www.cpantesters.org/cpan/report/09d57d08-ea29-11e5-9af5-f295bf69c04f

t/20-simple.t

@@ -98,12 +98,12 @@ SKIP: {
     skip "this test does not work with msysgit on Win32", 4
         if $^O eq 'MSWin32';
 
-    ok( my $cmd = $r->command('commit'), 'git commit' );
+    ok( my $cmd = $r->command('commit', '--no-verify'), 'git commit' );
     isa_ok( $cmd, 'Git::Repository::Command' );
     local $/ = "\n";
     my $error = $cmd->stderr->getline;
     my $git = Git::Repository::Command::_is_git('git');
-    is_deeply( [ $cmd->cmdline ], [ $git, 'commit' ], 'command-line' );
+    is_deeply( [ $cmd->cmdline ], [ $git, 'commit', '--no-verify' ], 'command-line' );
     $cmd->close;
     like(
         $error,

t/30-test_repository.t

@@ -33,7 +33,7 @@ my $file = 'hello.txt';
     print $fh "Hello, world!\n";
 }
 $r->run( add => $file );
-$r->run( commit => '-m' => 'hello' );
+$r->run( qw( commit --no-verify -m hello ) );
 my $sha1 = $r->run( 'rev-parse' => 'master' );
 
 # expect test_repository to fail