Support for passwords with spaces

At present jet doesn't support passwords with spaces in them. 

I was able to workaround the issue by doing a sql-injection like attack:

```go
	err := postgres.Generate("./gen/db", postgres.DBConnection{
		Host:     "localhost",
		Port:     5432,
		User:     "dbuser",
		SslMode:  "disable",
		Password: "null password='password with spaces'",
		DBName:   "mydb",
	})
```