ENYO-2904: replace dependency on `node-unzip` by `node-zip`|`JSZip`

- no more stream-based unzipping: the entire ZIP archive is now loaded
  in memory (as a Buffer).
- note to reviewer: `_unzipFile()` is indeed kept as a single function (even with multiple nested `async.*`) to keep it on a single page.

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>