* installcheck/Amanda_Rest_Dumps.pl: Check the Dumps endpoint
* installcheck/Amanda_Rest_Storages.pl: Check the Storages endpoint
* installcheck/Installcheck/Config.pm: Add policy and storage.
* installcheck/Makefile.am: Add Amanda_Rest_Dumps and
  Amanda_Rest_Storages.
* perl/Amanda/Changer.pm, perl/Amanda/Changer/diskflat.pm,
  perl/Amanda/Storage.pm: Change many Amanda::Changer::Error to be
  Amanda::Message compliant.
* perl/Amanda/Rest/Storages.pm: Pass the tapelist to the storage.


git-svn-id: https://svn.code.sf.net/p/amanda/code/amanda/trunk@5770 a8d146d6-cc15-0410-8900-af154a0219e0