restapi: REST API to stop migrate on brick

REST API for stopping the already started migrate brick asynchronous
task on a gluster volume.

Usage:
    - api/clusters/<cluster-Id>/glustervolumes/<volume-id>/bricks/stopmigrate

Input Parameters:
    <action>
        <bricks>
            <brick>
                <name><Brick1-Name></name>
            </brick>
            <brick>
                <name><Brick2-Name></name>
            </brick>
        </bricks>
    </action>

Change-Id: I0bba03cf04bed8041cb4e25cac0748afbeed2261
Signed-off-by: Shubhendu Tripathi <shtripat@redhat.com>