Removed fs-ext dependency, so now everything builds and runs on vanilla Windows 10 (WSL not required)

[doctorjei]

Reasons:

1.fs-ext doesn't work on Windows and is no longer necessary (Node7 incorporated needed functionality.)

2. Mimetype detection incorrectly returned "coffeescript" for any file with more than one "."; fixed.
3. "build-debug" target added to grunt to simplify debugging ("uglify" makes this harder than necessary)