Refactor author usage into WP_Stream_Author class; use System user always
Fix assignment alignment issue for PHPCS
Use Unknown user instead of System user
Fix coding style to use elseif
Use N/A instead of Unknown
Remove unused variable
Introduce author agent concept and logging WP Cron

See #431
Essentially a port of WP Internal Pointers for Stream. Needs work to allow extensions to hook into it.
Use global $wp_roles instead of $_GLOBALS['wp_roles']

Possible fix for #468
 global fallback
Change some variable names
Single statement blocks still need brackets
Modified to allow other extensions to more easily add their own admin pointers through this class.
Merge remote-tracking branch 'origin/develop' into issue-466
Fixed phpcs errors.
Implemented 'load' setup method, also added missing braces and switched escaping to JSON encoding.
Removed superfluous quotes from JSON encoded output.
Now using proper constants for hooks
Added mechanism to specify a constant for affiliate ID to be used in the Extensions page. Fixes #482.
Escaping of affiliate ID constant now more appropriate for an expected integer