ISPN-4966 The <backups/> element should be a sub-element of all cache-types, not just clustered caches
Update locking documentation

* added how it works in clustered caches
ISPN-4970 AvailabilityException and AvailabilityMode are in the wrong package
ISPN-4970 AvailabilityException and AvailabilityMode are in the wrong package

Move the impl package as well
ISPN-4981 Update to Hibernate Search 5.0.0.Beta2
ISPN-4981 Spatial Query updated API: onCoordinates -> onField
ISPN-3743

Ignore some of the errors that can be thrown by a node while stopping:
IllegalStateException and NullPointerException.