Fix: remove file path matching for dev nunjucks watcher

[tjk911]

When we make changes to the _layouts folder, the nunjucks watch function sees it but does not rebuild associated pages.

Issue example:

1. Make change to _layouts/header.html
2. Check localhost:3000
3. Nothing changes

We noticed it would work if we:

1. Make change to _layouts/header.html
2. Save index.html
3. Check localhost:3000
4. See changes

With help from @brandonrobertz, we tracked it down to the lib/engines/nunjucks.js file.

We suspect that

    if (file !== path)
        continue;

was ignoring layouts changes because it would see that _layouts/header.html != index.html and ignore it. Removing this seemed to have fixed this issue.

[brandonrobertz]

Some context: when I wrote this onChange handler, I cobbled code together from other places and wasn't 100% sure if this file !== path check was important or not. So I included it just in case. I think it's probably safe to remove it and rebuild all the files whenever we notice a change. This actually explains some odd behavior I've seen in the past (no show stoppers just annoyances) and this PR should fix those.