[#1208] Use search to get datasets on group_show

Use the search rather than query the db.

Instead of returning the whole package dict, pick the fields to match
the ones currently returned by the API.
[#1208] Do not query datasets on group_show from the controller

When dictizing the group as requested from the controller, don't query
Solr for datasets as they will be ignored and get requested on the
controller later on anyway
[#1208] Return whole dicts on package listing for group_show

The reason is that this is consistent with other package listings
(tag_show, package_search) and at the same time is backwards compatible
as it keeps all the existing fields.

Users would be able to choose not to return the packages list.
[#1208] Allow users to not request the dataset listing on group_show
[#1208] Ignore __junk field in group schema

It surfaced on the tests due to the new list fields (resources, tags...)
in the group's datasets
Merge branch 'master' into 1208-dictize-changes-2
[#1208] Fix wrong logic for search params
[#1208] More robust boolean param handling
[#1208] Add new tests for group/org list/show

Added a couple of factories for groups and orgs. Not clear about the
user that should be creating them.
[#1208] Fix tests Pep8 and horrible and unmaintaineble dictization tests
Merge branch '1208-dictize-changes-2'