Replace implementation specific code with generalized user-locator
implementations that can be re-used by more notifications in other
extensions.
This patch adjusts the `user-locators` notification parameter to allow
arrays which facilitate passing options to the locator.
Previously(still works):
'user-locators' => array( 'foo', 'bar' ),
New functionality:
'user-locators' => array(
'foo',
array( 'bar', 42 )
)
In the second example the callback specified by `bar` will receive
an EchoEvent as the first argument and array( 42 ) as its second
argument.
Change-Id: I7305279bc91d1e40e7054e2fd42a819a35526b82
