ENYO-2775: add file-system overlays & use it for Designer IFrame

- query-parameter `?overlay=designer` causes the files under
  `$deimos/source/designer/iframe/` to be present in any folder
  requested by the client.  This is stateless.
- Ares Designer now sits on top of the application, with IFrame-specific
  files (as defined by `iframe.html`) to be loaded _on-top_ of the
  application files.
- Note: as the file-system service is un-aware of the project root
  folder, overlaid files are present in _every_ folder as soon as the
  query parameter is present.

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-2775, ENYO-1741: fix regression on error handling

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-2775: drop deprecated `util.pump()`

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-2775, ENYO-2901: re-enable file-system test suite

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-2775: apaise jshint + sanitize logging

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
Merge remote-tracking branch 'origin' into ENYO-2775

Conflicts:
	hermes/fsLocal.js
ENYO-2775: fix console error on IE10

- But IE10 still crashes.

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-2775: use overlays for less & add non-reg unit test

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
Merge branch 'ENYO-2775' of github.com:enyojs/ares-project into ENYO-2775

# By Francois-Xavier Kowalski
# Via Francois-Xavier Kowalski
* 'ENYO-2775' of github.com:enyojs/ares-project:
  ENYO-2775: fix console error on IE10
Merge branch 'master' of github.com:enyojs/ares-project into ENYO-2775

Conflicts:
	ares/source/Ares.js
Merge pull request #485 from enyojs/ENYO-2775

ENYO-2775: add file-system overlays & use it for Designer IFrame