Sourcemap support

Implemented support for SourceMaps for scripts loaded in debugger.

Fixed handling of hidden files configuration, so that the configured regexs
are executed on file paths reported by V8 instead of file:// URLs used by
front-end.

*Limitations*

It is not possible to apply sourcemap before the file is loaded into V8,
since that feature is not implemented in Blink's DevTools. This means that
you cannot debug module loading of coffeescript modules in coffee-script,
you have to dive into transpiled javascript to set breakpoints.

Live-edit does not work at all for sourcemapped files, you cannot edit
your coffeescript files in node-inspector.

Closes issue #17.

@Schoonology please review.