Revision 193082

Resolving: MNG-495

o Pressing [ENTER] at a plugin update prompt should result in the plugin being registered, as indicated by the prompt.
o Use CLI switch '--no-plugin-updates' to suppress usage of the plugin registry
o Use CLI switch '--update-plugins' to force updated/resolved plugin versions to be registered
o Neither of these has a short CLI option, since we're starting to run out of sensible char options for these types of things.