"Import" button is not shown even if the user has permission to use an import plugin in a given context

[Nicklas Nordborg]

From a comment in ticket #473:

Another problem related to configuration imports I encountered was that after importing a reporter importer configuration (affymetrix) as 'root' but trying to import as 'admin' (role 'Administrator') there was to import tab. I tried to share the configuration to 'admin' but there was still no import tab in the reporters page for 'admin'. So 'admin' took ownership for this configuration, and after this steal 'admin' could import reporters. This was tested on the latest revision (3070) in the trunk.

[Nicklas Nordborg]

There are two problems that together creates a strange behaviour:

1. The 'admin' user has to logout and login or use the 'File -> Reload permissions' or wait some time (~5-10 minutes) menu before the newly shared import configuration is visible.

2. The PluginDefinition.countPlugins() method doesn't consider permissions given by role membership. The 'admin' user should have access to all plugins, but it is not reflected by this method. This needs to be fixed.

[Nicklas Nordborg]

(In [3074]) Fixes #476: "Import" button is not shown even if the user has permission to use an import plugin in a given context