Add a convenience function to restrict locks to a given set
Add a convenience function to restrict locks to a given set

As it is an operation the locking daemon is supposed to provide,
add a function restricting the locks of a user to a given list
and release all other locks.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

andir/ganeti,mbakke/ganeti,yiannist/ganeti,onponomarev/ganeti,dimara/ganeti,grnet/snf-ganeti,grnet/snf-ganeti,leshchevds/ganeti,leshchevds/ganeti,yiannist/ganeti,mbakke/ganeti,bitemyapp/ganeti,ganeti/ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,apyrgio/ganeti,ganeti/ganeti,dimara/ganeti,andir/ganeti,apyrgio/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,andir/ganeti,bitemyapp/ganeti