clear 3 compiler warnings (unsigned vs signed). go to 2 overlapped levels from 3 (upgrade issue). adjust VersionSet::Finalize() penalty values again based upon testing.
Add routine to pause DBImpl::Recover while new overlapped areas are cleared via compactions (Riak 1.3 to 1.4 conversion).  Also cleaned some int versus size_t compiler warnings.
move throttle and reduce mutex_ lock calls by one.  change factor in Finalize() back to 8, was 2 recently (2i_slf_stressmix test)
perf top indicates the pthread timed wait was heavy hitter.  reduced number of times a compaction thread call PrioritizeWork() to reduce unnecessary overhead.  compactions are running too slow in 2i_slf_stressmix
Move the DB::Open pause code to new location so as to let foreground processing of recovery logs properly post to version_set before starting background compactions.
Merge pull request #84 from basho/mv-level-work3