don't rely on Makefile for build (tkasparek@redhat.com)

build just backend-libs, nothing else is needed for RHEL8

don't run pyling when building spacewalk backend + other build fixes

Update to use newly separated spacewalk-python[2|3]-pylint packages

1540981 - Clarify error-reporting when checksum_cache is bad

clean up specfile

fix pylint 2.0

fix pylint warnings

support syncing of modules during ISS
export modules in rhn-satellite-exporter
support downloading modules.yaml from backend
retrieve module metadata when syncing yum type repository
provide a way how to retrieve module files for yum type repositories

1537098 - Teach packageImport to ignore flags RPM doesn't know

Fix syncing severity

1538096 - Security erratum severity is not being synced using synchronization

1534417 - hide plaintext password in spacewalk-debug archive

Keep the authtoken appended to the URL when downloading repo content

1507553 - include unmapped channels in channel list and EOL channel list
1507553 - change message to warning and don't display with default verbose

still can print custom channels with CDN repos without mappings
1525858 - add --list-eol option to show more info about channel's end-of-life