Revision 191021

Resolving issue: MNG-379

o Added support for update-all and update-none when prompting the user.

o Added --update-plugins/-F option to force an update of the plugins used in the project.

o Added autoUpdate setting for the plugin registry. This is used when in non-interactive mode, to determine whether to register plugin updates

o Added updateInterval to determine when/how often to check for updates to registered plugins. Supports three syntaxes:

  - 'never'
  - 'always'
  - 'interval:XXX' (where XXX can be a combination of weeks, days, hours, and minutes in the syntax: 1w1d1h1m)
         > this renders the interval syntax similar to 'interval:1w' to check every week.

  NOTE: update intervals are calculated from the time a particular plugin was last checked.

o Added lastChecked attribute for registered plugins, to use as a basis for calculating update-check interval

o Added RuntimeInfo classes for maven-settings and maven-plugin-registry, to help in tracking the file each instance comes from, in addition to merging info which is useful when extracting the user-level instance from the merged instance (for persisting changes to the user instance, f.e.).

o Changed verifyPlugin(..) to take an instance of Settings, to allow persistent decisions across the session (like update-all, update-none in the plugin version manager)

This should take care of outstanding issues with this new feature. I'm closing the JIRA issue now, and we'll deal with any bugs/shortcomings as separate issues.