Fix download source/working directory detection.
Fix download source/working directory detection.

Resolve the absolute path of folders and use `filepath.HasPrefix` to
detect if the source is in the working source directory.

Signed-off-by: Vincent Demeester <b98c0fd48a8945096c766de790fe70420dd2f223@redhat.com>

coreydaley/source-to-image,bparees/source-to-image,mfojtik/source-to-image,bparees/source-to-image,coreydaley/source-to-image,soltysh/source-to-image,mfojtik/source-to-image,gabemontero/source-to-image,openshift/source-to-image,gabemontero/source-to-image,openshift/source-to-image,bparees/source-to-image,soltysh/source-to-image,soltysh/source-to-image,gabemontero/source-to-image,bparees/source-to-image,soltysh/source-to-image,openshift/source-to-image,mfojtik/source-to-image,gabemontero/source-to-image,mfojtik/source-to-image,coreydaley/source-to-image,coreydaley/source-to-image