medium: utils: ask() did not respect force flag in all cases (bnc#868007)

Interactive ask() should become a force-flag check when
non-interactive, and silently succeed if force is set even
if interactive.
medium: scripts: corosync uses mcastport - 1 (bnc#868008)

corosync uses both UDP port <mcastport> and <mcastport> - 1 for
communication.
parse: More liberal parsing of role assignment in constraint rules

Allow both $role=<role> and role=<role> in constraint rules.
test: xmlutil: Test case for options comparison
medium: xmlutil: fencing-topology used broken comparison (bnc#866639)

With the new xml_equals function, use the same comparison function
for all tags. Sort attributes by both key and value to ensure correct
comparison for fencing-topology.