added; "track" option plugin to list
changed; "standard meta" pattern now enables list "track" option
added; "standard meta" pattern displays deprecation warning
added; unit test for list "track" option
added; helper functions for commonly used code
changed; _req_user.test to use helper functions
added; "track" option documentation to Keystone docs
formatting/phrasing changes to 'track' doc
phrasing changes to deprecation warning message (to match docs)
Merge pull request #523 from JohnnyEstilles/feature/adding-list-track-option

Adding List 'track' option (replaces #490)