Dependencies update and database not available crash fix.

Added forgotten dependencies update.

Fixed fastpastebin crash when database isn't available and added cute
error screen for informing users about such condition (both HTML and raw).

cmd/fastpastebin/fastpastebin.go

@@ -31,6 +31,7 @@ import (
 	"syscall"
 
 	// local
+	"gitlab.com/pztrn/fastpastebin/domains/database_not_available"
 	"gitlab.com/pztrn/fastpastebin/domains/indexpage"
 	"gitlab.com/pztrn/fastpastebin/domains/pastes"
 	"gitlab.com/pztrn/fastpastebin/internal/captcha"
@@ -60,6 +61,7 @@ func main() {
 
 	captcha.New(c)
 
+	database_not_available.New(c)
 	indexpage.New(c)
 	pastes.New(c)