Support checking for su user to atomic_move

Fixes #7553
Check groupnames for None as well as an empty string in add_host

Fixes #7585
corrected doc example, non existing fact to the 2 it had 'merged'
Merge pull request #7595 from bcoca/doc_include_vars_fix

corrected doc example, non existing fact to the 2 it had 'merged'
template.py: Handle purposely raised exceptions in lookup()

If a lookup plugin is run by the lookup() template method it should pass
along any AnsibleError (or child exception classes) rather than just eat
them.  These exceptions are purposely raised by the plugin.
Merge pull request #7609 from jimi-c/issue_7553_su_copy

Support checking for su user to atomic_move
updating example, to be more consistent with parameter names
Merge pull request #7608 from jjneely/lookup-function

template.py: Handle purposely raised exceptions in lookup()
Merge pull request #7610 from CorbanR/devel

updating ec2_group example, to be more consistent with parameter names