Fixing Windows path issues by removing the replaceSlashes calls.

I had the following issues on Windows:
* I tried to create a file with this kind of name : `app/{{name}}-file.js` with, for example the name `test`. The result was the following file : `app\{name}}-file.js` while it should have been `app\test-file.js`.

* Using slashes in Handlebars helpers in paths (example: `app/{{#camelize}}{{name}}{{/camelize}}-file.js`) caused an error preventing the files from being generated. The error stated : (also described in issue https://github.com/paulmillr/scaffolt/issues/28)
```
Error: Parse error on line 1:
...camelize}}{{name}}{{\camelize}}-file.js
-----------------------^
Expecting 'ID', 'DATA', got 'INVALID'
```

I believe these errors were caused by slashes being replaced by backslashes. Backslashes then caused inappropriate escaping of some characters / inappropriate behavior of the `exports.formatTemplate` function.
I removed the `replaceSlashes` calls (and the function altogether, since it's not called anywhere anymore).
I also removed a `sysPath.join` call that was introducing another backslash. 

I think paths should not be OS-dependent until they're completely formatted. Keep the `/`'s until the file is ready to be written.

As far as I could test, Linux behavior is unaffected by these changes. Would be cool to have some automated tests though :).

fixes https://github.com/paulmillr/scaffolt/issues/28