[migration] Enforces absolute pathnames for EOS dir/file injection

Now we are also tolerant of whether paths in config file do or do
not have a trailing slash.

Pathnames from the DB must have a leading slash if we have to strip off
the CASTOR prefix, but in any case we will convert all filenames to
absolute filenames by adding the EOS prefix.

cta.spec.in

@@ -310,7 +310,6 @@ directory metadata into the EOS namespace.
 %attr(0755,root,root) %{_bindir}/eos-import-files
 %attr(0755,root,root) %{_bindir}/eos-test-dir-inject
 %attr(0755,root,root) %{_bindir}/eos-test-file-inject
-%attr(0755,root,root) %{_bindir}/eos-insert-missing-dirs
 %attr(0755,root,root) %{_bindir}/json-pretty-print.sh
 %attr(0755,root,root) %{_bindir}/startvoexport.sh
 %attr(0755,root,root) %{_bindir}/exporttapepool.sh