gluster: Introduced GlusterTaskUtils

Introduced a utility class GlusterTaskUtils.
This class provides gluster asynchronous tasks related utiltity methods
like isTaskOfType() and isTaskStatus(). These methods check the
different field values related to asynchronous task on a given volume.

Change-Id: Ib58610601c64f16796962d0ebf8643fa591b82e6
Signed-off-by: Shubhendu Tripathi <shtripat@redhat.com>