Core: Fix of bug in method deleteResource() from ResourceManagerBl
 - moddified deleteResource() in ResourceManagerBlImpl
    - deleteResource() now remove all non-virtual resource-group attributes from database
 - added new method removeAllGroupResourceAttributes() into AttributesManager
Merge branch 'resource_attrs' of https://github.com/papperwing/perun into kubaTask01-Fix_delete_resource_bug
Use removeGroupFromResource method from BlImpl

- method from Impl does not delete group_resource attributes
- need to use method from BlImpl
- method in BlImpl has own log message to auditer
- add simple test
Merge pull request #328 from stavamichal/kubaTask01-Fix_delete_resource_bug

delete resource with all group resource attributes