Implement the LevelDB API, backed by WiredTiger.
Merge branch 'develop' into leveldb-api
Add configure support for enabling LevelDB, including the HyperLevelDB flavor.
Fix some stray copyright warnings.
Only visit the LevelDB directory if configured.
Map LevelDB configuration onto WiredTiger.
Merge branch 'develop' into leveldb-api
Fix build of HyperLevelDB support.
Fix the LevelDB table configuration, implement compact, avoid a nasty race on shutdown.
Implement DestroyDB in the LevelDB API, fix Open to optionally create the directory.
Bump the default number of sessions for LevelDB, until we figure out how to safely close the sessions when threads exit (db_bench creates multiple sets of threads on the same connection).

Also make DestoryDB quieter: check for the existence of the special "WiredTiger" file before attempting to open.
Remove debugging output from LevelDB
Merge branch 'develop' into leveldb-api
Remove references to Value from LevelDB. It's not present in 1.13.
Merge pull request #1046 from wiredtiger/leveldb-api-noValue

Remove references to Value from LevelDB. It's not present in 1.13.
Implement the LevelDB Cache class, so that applications can safely delete the object we give them.  Bump the cache size so that it can include at least 25 chunks.
Fix iteration termination: WT_NOTFOUND is not an error.  Also reset cursors after removes.
Turn on logging for LevelDB, to match the default durability level.
Add exclusive option to wiredtiger_open.

Also add error return for LevelDB::Open if create isn't specified.
Actually pay attention to wiredtiger_open exclusive option.