Consistent use of OperationPresence.

Don't get a provider as a OperationPresence, and then cast it to a
OperationPersistentPresence. If a provider doesn't implement both
this will cause a ClassCastException.
Enable IRC bundles
IRC Account Registration Wizard doesn't activate

Use the AbstractServiceDependantActivator to ensure the UIService
is available when the plugin is activated.
Correct the labels for fields in the IRC Wizard

Show a semicolon after the field name, and
correctly reference the PORT label.