Fixes #3102 - listing associated resources

- associated resources are now referenced by names
- ids can be displayed if required (flag --show-ids)
- new formatters and filed types for associations
- Fields::SingleReference is a temporary solution until all references the api returns are nested
- shared associations extracted into modules
More readable output of failed tests for column presence

It now displays only comparison of the title headers and not the data.
Refs #3102 - reference definition turned into functions
Merge pull request #118 from tstrachota/assoc

 Fixes #3102 - listing associated resources