initial mapdb commit (add depend + planning)

after a lot of thinking, it seems as though most of the optimal
solutions involve possibly large scale changes to mapdb. I am
deferring those for now to attempt to establish a baseline
seems functional and passes bdb byte store's tests

probably a hundred and one things lurking in the shadow, performance
optimizations to be made, and then theres the part where the whole
thing is terribly interfaces, but this is an okay start maybe
bit of logging and fix for skip list cache
Merge branch 'master' into mapdb

Conflicts:
	hydra-store/src/main/java/com/addthis/hydra/store/kv/ReadExternalPagedStore.java
	hydra-store/src/main/java/com/addthis/hydra/store/skiplist/SkipListCache.java
Merge pull request #88 from addthis/mapdb

Mapdb Support