Cache.remove(K) should always invoke the CacheWriter (even if no entry
exists in the cache)

In the words of christall:
"absence of a cache entry should not be used to veto a write"
Merge pull request #166 from timeck/removeAlwaysCallsWriter

Cache.remove(K) should always invoke the CacheWriter (even if no entry exists in the cache)
most of 107 tck is passsing