Merge pull request #346 from hhovsepy/master

added more checks, some workaround on system subscription to skip blocker bugs
new content definition filter methods and tests
Merge pull request #347 from alda519/include_errata_filter_337

new content definition filter methods and tests
missed headpin-cli for the setUp of Systems cli tests
Merge pull request #350 from hhovsepy/master

fixed failing tests
errata rule fixed - date_range bad format, not a bug
add_rule method comments, package and package_group tests
Merge pull request #353 from alda519/filter_package_group_339_340

new filter package and package_group tests
Added test for ID 259835
Merge pull request #354 from tkolhar/master

Added test for ID : 259835
did some reordering of rests, added comments with bugs, fixed failing
ones