Let client set full path including access_id

In the past the client would specify everyting but the root directory
and the root directory would automatically be set based on the access_id
being authenticated with. That meant that the client wouldn't store the
access_id part of the path and would have to prepend it dynamically based
off it's settings.

But this causes problems if one application has to access files uploaded
by two different clients with two different access_ids.

So now we're letting the client store and set the full path which will
include the root access_id directory becasuse carrierwave-roz will
prepend and store it automatically.