gRPC user needs to be in EOS +sudo group

castor-dbtools is required by cta-migration-tools

Added activable logs to the RetrieveQueueStatistics cache for debugging

An example value of sys.retrieve.error is as follows:

[itctabuild02] ~ > sudo eos attr ls /eos/dev/userfiles/testdir_1/test_1 | grep sys.retrieve.error
sys.retrieve.error="Garbage collected at 2019/09/09 16:27:26.609570"
[itctabuild02] ~ >

This can now be done without tearing down and re-creating the containers.

Added error messages in case of problems for easier diagnosis.

Conflicts:
	continuousintegration/docker/ctafrontend/cc7/opt/run/bin/ctaeos-mgm.sh

Conflicts:
	continuousintegration/orchestration/tests/repack_systemtest_wrapper.sh

Added report generation to repack_generate_report.sh so that it honours the repack "add copies only" and the repack "Move and add copies"

Changed repack CI test to test the Add Copies workflow (need reporting though)

Added a check for the repack just add copies workflow that verify that two archive routes does not point to the same tapepool

Remove the repack buffer if the repack expansion indicates that no Retrieve is necessary
Corrected the XrootDirectory::exist() method

This version contains several fixes required by the migration tools:
- fixes bug where quota bit was set when directory permissions have
  "executable by all" bit set
- inheritance of extended attributes
- better reporting of errors in case of failure