Add rax_meta module

Also update rax to mirror meta value normalization from rax_meta
Removing cruft leftover from the deprecation of include+with_items

Also cleaning up integration tests that had checks for the empty item
attribute in certain results.

Fixes #7535
made nested lists diff lengths - caused confusion

As a relatively-new user to Ansible, the Nested Loop example made me think it was looping through both lists together (`alice` would go with `clientdb`, `bob` with `employeedb`) and not actually nested. I realize now I was just being stupid, but I feel making the example lists different lengths would prevent such confusion in the future.
Fix order of merging variables for the combined cache

Fixes #7598
Merge branch 'rax-meta' of https://github.com/sivel/ansible into sivel-rax-meta
Adding the new rax_meta module to the CHANGELOG
Merge branch 'sivel-rax-meta' into devel
Merge pull request #7656 from tsemerad/patch-1

made nested lists diff lengths - caused confusion
Tweaking make_su_cmd test

Fixes #7652
Fix error passing play vars to an included playbook with empty vars

Fixes #7658
Clarified, remote_user config item does override ansible current user if defined.
Merge pull request #7662 from billcarlson/devel

Clarified, remote_user config item does override ansible current user
Fixing version_added strings for new features in ec2_elb_lb

Fixes #7631
Add additional params to get_target_from_rule method in ec2_group

Fixes #7592
Add rackconnect and managed cloud automation check examples