Null not handled on process names

[FrostyCoolSlug]

Hi,

This is likely related to 714e5f1 and #3, in the current master, NULL characters aren't being correctly handled when creating the pname, so the following code:

let tasks = tasklist::Tasklist::new();
tasks.for_each(|task| println!("{}", task.get_pname()));

Will output tasks like:
svchost.exe

So the process name, and enough null characters up to 260 characters, so looks like get_proc_name isn't handling the null termination correctly.