Merge pull request #47 from espadrine/master

text/plain files have type text.
Pencil uses Fleau.
[gateway] make search blazing fast
[meta] fix malformed "text" mime type
[gateway] multi-file uploads from the toolbar
Pencil uses Fleau.
Spec-compliant file upload.

According to spec, an iframe's browsing context is determined by its name.
As a result, the upload (while working) seemed wrong in Firefox from a UX
standpoint: a pop-up showed up with a scary message.