utils: Create AsyncProcessOperation

This is an object to wrap a process so it can be treated as an
AsyncOperation.

Features:
* Takes care of pid collection
* Has pluggable output parsing
* Process appropriate implementation of wait() and stop()

Related-Bug-Url: http://bugzilla.redhat.com/964595
Change-Id: I79d0eefc9d917a4a93916d52867fb4f1e793c60e
Signed-off-by: Saggi Mizrahi <smizrahi@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/21135
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Tested-by: Yaniv Bronhaim <ybronhei@redhat.com>