Tests: added has_daemon() support for win32.

See for details:
https://technet.microsoft.com/en-us/library/bb490909.aspx
https://technet.microsoft.com/en-us/library/bb490998.aspx

lib/Test/Nginx.pm

diff --git a/lib/Test/Nginx.pm b/lib/Test/Nginx.pm
index 0a45181..9939793 100644
--- a/lib/Test/Nginx.pm
+++ b/lib/Test/Nginx.pm
@@ -261,7 +261,8 @@
 	my ($self, $daemon) = @_;
 
 	if ($^O eq 'MSWin32') {
-		Test::More::plan(skip_all => "win32");
+		`for %i in ($daemon.exe) do \@echo | set /p x=%~\$PATH:i`
+			or Test::More::plan(skip_all => "$daemon not found");
 		return $self;
 	}