Remove the LowLevelStorageService and supporting classes
Refactor CacheEntry classes to wrap a jcr property, whereever it is
stored

- getFixity() should return a collection of fixity results that provide
  one or more fixity results for all copies of the binary data
- simplify the infinispan distributed executation calls for ISPN-backed
  binary stores
remove unused test imports
Remove unused import from ServiceHelpers
Change copyright date to match new checkstyle rules