Fixed a small bug where the error message for file-not-found was wrong when -a was used
fixed a bug where the chdir happened before the opening of the har file.
This resulted in harx never finding the file it should actually open as
the directory that was used for exporting to different from the current
dir, so the chdir before opening fileName invalidated the path and
fileName could not be openend.I fixed this bug by prepending the
directory that is given as the -a argument to each dump call.
Merge pull request #1 from terhechte/master

I fixed two small issues.