[CHEF-3399] Make data_bag_path an array like cookbook_path
[CHEF-3399] data bag solo tests cleanup
[CHEF-3399] better place for stub helpers
[CHEF-3399] Use first seen data bag (do not overwrite). Tests.
[CHEF-3399] Raise in case of data bag items conflict. Tests.
[CHEF-3399] Tests: check data_bag_path instead of @paths.
Merge pull request #1177 from xeron/CHEF-3399

[CHEF-3399] Make data_bag_path an array like cookbook_path