Stricter #get() operation

[SBoudrias]

Right now #get() will return file pointer if we try to get a directory. We should be stricter about that and throw if what we try to get is not a file.

Same thing about permissions issue. We shouldn't have a catch all clause - ideally we'd only catch read errors.

[SBoudrias]

A complexity issue here is that a file may not have any extension. So how do we differentiate those from folders? I'm not sure anymore if it is possible.