core: task monitoring for import glance image

In order for import glance image task to be monitored correctly,
internal action invocation should get enclosingCommand's original
context (see tasks tab screenshot [1]).

[1] http://i.imgur.com/aFIA1p0.jpg

Change-Id: I6780e8a18934bcd22e099dd5ea9d7e726ed60193
Bug-Url: https://bugzilla.redhat.com/1119325
Signed-off-by: Daniel Erez <derez@redhat.com>