Removed the old security system.

Signed-off-by: Wolf480pl <wolf480@interia.pl>
Added CommonPolicy.CommonPermissionCollection

Signed-off-by: Wolf480pl <wolf480@interia.pl>
Added YamlConfiguration to CommonPolicy

Signed-off-by: Wolf480pl <wolf480@interia.pl>
Added BrowserPermission
Added Client.openBrowser(URI)

Signed-off-by: Wolf480pl <wolf480@interia.pl>
Added required and optional clearances to PluginDescriptionFile.
Don't load the plugin at all, if the required clearances are not
granted.
Started adding default plugin permissions.
Added ClassLoaderFactory
Added OptOutPermission, it will bee needed for (Almost)AllClearance
Added one more permission to default plugin permissions.
Improved CommonPolicy.getPermissions()
Added doPrivileged in CommonPolicy to avoid StackOverflow.
Maven Clean (license headers)
Started adding doPrivileged where needed.
Added one more permission to default plugin permissions.
Improvements in CommonPermissionCollecton and OptOutPermission
Renamed OptOutPermission to IncludeExcludePermission. Added plugin
permission exclusions.
Let's give plugins permission to the resource system.
Fixed some StackOverflow in CommonPermissionCollection, too.