ENYO-1740: Hermes: implement generic PUT

- put() now sits into fsBase
- fsBase#put() now dispatches requests between fsBase#putWebForm() &
  fsBase#putMultipart(), both using putFile() as storage back-end.
- implement fsLocal#putFile() & cleanly fail fsDropbox#putFile()
- test all of the above with mocha
- update OUT request format in documentation

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>